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Software / API Bindings / C/C++ / API Reference and Examples / Bricklets / RS485 Bricklet

C/C++ - RS485 Bricklet

This is the description of the C/C++ API bindings for the RS485 Bricklet. General information and technical specifications for the RS485 Bricklet are summarized in its hardware description.

An installation guide for the C/C++ API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Modbus Master

Download (example_modbus_master.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_rs485.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your RS485 Bricklet

// Callback function for Modbus master write single register response callback
void cb_modbus_master_write_single_register_response(uint8_t request_id,
                                                     int8_t exception_code,
                                                     void *user_data) {
    uint8_t expected_request_id = *(uint8_t *)user_data;

    printf("Request ID: %u\n", request_id);
    printf("Exception Code: %d\n", exception_code);

    if (request_id != expected_request_id) {
        printf("Error: Unexpected request ID\n");
    }
}

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    RS485 rs485;
    rs485_create(&rs485, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Set operating mode to Modbus RTU master
    rs485_set_mode(&rs485, RS485_MODE_MODBUS_MASTER_RTU);

    // Modbus specific configuration:
    // - slave address = 1 (unused in master mode)
    // - master request timeout = 1000ms
    rs485_set_modbus_configuration(&rs485, 1, 1000);

    // Register Modbus master write single register response callback to function
    // cb_modbus_master_write_single_register_response
    uint8_t expected_request_id = 0;
    rs485_register_callback(&rs485,
                            RS485_CALLBACK_MODBUS_MASTER_WRITE_SINGLE_REGISTER_RESPONSE,
                            (void (*)(void))cb_modbus_master_write_single_register_response,
                            (void *)&expected_request_id);

    // Write 65535 to register 42 of slave 17
    rs485_modbus_master_write_single_register(&rs485, 17, 42, 65535, &expected_request_id);

    printf("Press key to exit\n");
    getchar();
    rs485_destroy(&rs485);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Modbus Slave

Download (example_modbus_slave.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_rs485.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your RS485 Bricklet

// Callback function for Modbus slave write single register request callback
void cb_modbus_slave_write_single_register_request(uint8_t request_id,
                                                   uint32_t register_address,
                                                   uint16_t register_value,
                                                   void *user_data) {
    RS485 *rs485 = (RS485 *)user_data;

    printf("Request ID: %d\n", request_id);
    printf("Register Address: %d\n", register_address);
    printf("Register Value: %d\n", register_value);

    if (register_address != 42) {
        printf("Error: Invalid register address\n");
        rs485_modbus_slave_report_exception(rs485, request_id, RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS);
    } else {
        rs485_modbus_slave_answer_write_single_register_request(rs485, request_id);
    }
}

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    RS485 rs485;
    rs485_create(&rs485, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Set operating mode to Modbus RTU slave
    rs485_set_mode(&rs485, RS485_MODE_MODBUS_SLAVE_RTU);

    // Modbus specific configuration:
    // - slave address = 17
    // - master request timeout = 0ms (unused in slave mode)
    rs485_set_modbus_configuration(&rs485, 17, 0);

    // Register Modbus slave write single register request callback to function
    // cb_modbus_slave_write_single_register_request
    rs485_register_callback(&rs485,
                            RS485_CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_REGISTER_REQUEST,
                            (void (*)(void))cb_modbus_slave_write_single_register_request,
                            (void *)&rs485);

    printf("Press key to exit\n");
    getchar();
    rs485_destroy(&rs485);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Loopback

Download (example_loopback.c)

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#include <stdio.h>
#include <stdlib.h>

// For this example connect the RX+/- pins to TX+/- pins on the same Bricklet
// and configure the DIP switch on the Bricklet to full-duplex mode

#include "ip_connection.h"
#include "bricklet_rs485.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your RS485 Bricklet

// Callback function for read callback
void cb_read(char *message, uint16_t message_length, void *user_data) {
    char *buffer;

    (void)user_data; // avoid unused parameter warning

    // Assume that the message consists of ASCII characters and
    // convert it from an array of chars to a NUL-terminated string
    buffer = (char *)malloc(message_length + 1); // +1 for the NUL-terminator
    memcpy(buffer, message, message_length);
    buffer[message_length] = '\0';

    printf("Message: \"%s\"\n", buffer);
    free(buffer);
}

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    RS485 rs485;
    rs485_create(&rs485, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Enable full-duplex mode
    rs485_set_rs485_configuration(&rs485, 115200, RS485_PARITY_NONE, RS485_STOPBITS_1,
                                  RS485_WORDLENGTH_8, RS485_DUPLEX_FULL);

    // Register read callback to function cb_read
    rs485_register_callback(&rs485,
                            RS485_CALLBACK_READ,
                            (void (*)(void))cb_read,
                            NULL);

    // Enable read callback
    rs485_enable_read_callback(&rs485);

    // Write "test" string
    char buffer[] = {'t', 'e', 's', 't'};
    uint16_t written;
    rs485_write(&rs485, buffer, sizeof(buffer), &written);

    printf("Press key to exit\n");
    getchar();
    rs485_destroy(&rs485);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

API

Most functions of the C/C++ bindings return an error code (e_code). Data returned from the device, when a getter is called, is handled via output parameters. These parameters are labeled with the ret_ prefix.

Possible error codes are:

  • E_OK = 0
  • E_TIMEOUT = -1
  • E_NO_STREAM_SOCKET = -2
  • E_HOSTNAME_INVALID = -3
  • E_NO_CONNECT = -4
  • E_NO_THREAD = -5
  • E_NOT_ADDED = -6 (unused since C/C++ bindings version 2.0.0)
  • E_ALREADY_CONNECTED = -7
  • E_NOT_CONNECTED = -8
  • E_INVALID_PARAMETER = -9
  • E_NOT_SUPPORTED = -10
  • E_UNKNOWN_ERROR_CODE = -11
  • E_STREAM_OUT_OF_SYNC = -12
  • E_INVALID_UID = -13
  • E_NON_ASCII_CHAR_IN_SECRET = -14
  • E_WRONG_DEVICE_TYPE = -15
  • E_DEVICE_REPLACED = -16
  • E_WRONG_RESPONSE_LENGTH = -17

as defined in ip_connection.h.

All functions listed below are thread-safe.

Basic Functions

void rs485_create(RS485 *rs485, const char *uid, IPConnection *ipcon)
Parameters:
  • rs485 – Type: RS485 *
  • uid – Type: const char *
  • ipcon – Type: IPConnection *

Creates the device object rs485 with the unique device ID uid and adds it to the IPConnection ipcon:

RS485 rs485;
rs485_create(&rs485, "YOUR_DEVICE_UID", &ipcon);

This device object can be used after the IP connection has been connected.

void rs485_destroy(RS485 *rs485)
Parameters:
  • rs485 – Type: RS485 *

Removes the device object rs485 from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int rs485_write(RS485 *rs485, const char *message, uint16_t message_length, uint16_t *ret_message_written)
Parameters:
  • rs485 – Type: RS485 *
  • message – Type: const char *
  • message_length – Type: uint16_t
Output Parameters:
  • ret_message_written – Type: uint16_t, Range: [0 to 216 - 1]
Returns:
  • e_code – Type: int

Writes characters to the RS485 interface. The characters can be binary data, ASCII or similar is not necessary.

The return value is the number of characters that were written.

See rs485_set_rs485_configuration() for configuration possibilities regarding baudrate, parity and so on.

int rs485_read(RS485 *rs485, uint16_t length, char *ret_message, uint16_t *ret_message_length)
Parameters:
  • rs485 – Type: RS485 *
  • length – Type: uint16_t, Range: [0 to 216 - 1]
Output Parameters:
  • ret_message – Type: char *
  • ret_message_length – Type: uint16_t
Returns:
  • e_code – Type: int

Returns up to length characters from receive buffer.

Instead of polling with this function, you can also use callbacks. But note that this function will return available data only when the read callback is disabled. See rs485_enable_read_callback() and RS485_CALLBACK_READ callback.

int rs485_set_rs485_configuration(RS485 *rs485, uint32_t baudrate, uint8_t parity, uint8_t stopbits, uint8_t wordlength, uint8_t duplex)
Parameters:
  • rs485 – Type: RS485 *
  • baudrate – Type: uint32_t, Unit: 1 Bd, Range: [100 to 2000000], Default: 115200
  • parity – Type: uint8_t, Range: See constants, Default: 0
  • stopbits – Type: uint8_t, Range: See constants, Default: 1
  • wordlength – Type: uint8_t, Range: See constants, Default: 8
  • duplex – Type: uint8_t, Range: See constants, Default: 0
Returns:
  • e_code – Type: int

Sets the configuration for the RS485 communication.

The following constants are available for this function:

For parity:

  • RS485_PARITY_NONE = 0
  • RS485_PARITY_ODD = 1
  • RS485_PARITY_EVEN = 2

For stopbits:

  • RS485_STOPBITS_1 = 1
  • RS485_STOPBITS_2 = 2

For wordlength:

  • RS485_WORDLENGTH_5 = 5
  • RS485_WORDLENGTH_6 = 6
  • RS485_WORDLENGTH_7 = 7
  • RS485_WORDLENGTH_8 = 8

For duplex:

  • RS485_DUPLEX_HALF = 0
  • RS485_DUPLEX_FULL = 1
int rs485_get_rs485_configuration(RS485 *rs485, uint32_t *ret_baudrate, uint8_t *ret_parity, uint8_t *ret_stopbits, uint8_t *ret_wordlength, uint8_t *ret_duplex)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_baudrate – Type: uint32_t, Unit: 1 Bd, Range: [100 to 2000000], Default: 115200
  • ret_parity – Type: uint8_t, Range: See constants, Default: 0
  • ret_stopbits – Type: uint8_t, Range: See constants, Default: 1
  • ret_wordlength – Type: uint8_t, Range: See constants, Default: 8
  • ret_duplex – Type: uint8_t, Range: See constants, Default: 0
Returns:
  • e_code – Type: int

Returns the configuration as set by rs485_set_rs485_configuration().

The following constants are available for this function:

For ret_parity:

  • RS485_PARITY_NONE = 0
  • RS485_PARITY_ODD = 1
  • RS485_PARITY_EVEN = 2

For ret_stopbits:

  • RS485_STOPBITS_1 = 1
  • RS485_STOPBITS_2 = 2

For ret_wordlength:

  • RS485_WORDLENGTH_5 = 5
  • RS485_WORDLENGTH_6 = 6
  • RS485_WORDLENGTH_7 = 7
  • RS485_WORDLENGTH_8 = 8

For ret_duplex:

  • RS485_DUPLEX_HALF = 0
  • RS485_DUPLEX_FULL = 1
int rs485_set_modbus_configuration(RS485 *rs485, uint8_t slave_address, uint32_t master_request_timeout)
Parameters:
  • rs485 – Type: RS485 *
  • slave_address – Type: uint8_t, Range: [1 to 247], Default: 1
  • master_request_timeout – Type: uint32_t, Unit: 1 ms, Range: [0 to 232 - 1], Default: 1000
Returns:
  • e_code – Type: int

Sets the configuration for the RS485 Modbus communication. Available options:

  • Slave Address: Address to be used as the Modbus slave address in Modbus slave mode. Valid Modbus slave address range is 1 to 247.
  • Master Request Timeout: Specifies how long the master should wait for a response from a slave when in Modbus master mode.
int rs485_get_modbus_configuration(RS485 *rs485, uint8_t *ret_slave_address, uint32_t *ret_master_request_timeout)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_slave_address – Type: uint8_t, Range: [1 to 247], Default: 1
  • ret_master_request_timeout – Type: uint32_t, Unit: 1 ms, Range: [0 to 232 - 1], Default: 1000
Returns:
  • e_code – Type: int

Returns the configuration as set by rs485_set_modbus_configuration().

int rs485_set_mode(RS485 *rs485, uint8_t mode)
Parameters:
  • rs485 – Type: RS485 *
  • mode – Type: uint8_t, Range: See constants, Default: 0
Returns:
  • e_code – Type: int

Sets the mode of the Bricklet in which it operates. Available options are

  • RS485,
  • Modbus Master RTU and
  • Modbus Slave RTU.

The following constants are available for this function:

For mode:

  • RS485_MODE_RS485 = 0
  • RS485_MODE_MODBUS_MASTER_RTU = 1
  • RS485_MODE_MODBUS_SLAVE_RTU = 2
int rs485_get_mode(RS485 *rs485, uint8_t *ret_mode)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_mode – Type: uint8_t, Range: See constants, Default: 0
Returns:
  • e_code – Type: int

Returns the configuration as set by rs485_set_mode().

The following constants are available for this function:

For ret_mode:

  • RS485_MODE_RS485 = 0
  • RS485_MODE_MODBUS_MASTER_RTU = 1
  • RS485_MODE_MODBUS_SLAVE_RTU = 2

Advanced Functions

int rs485_set_communication_led_config(RS485 *rs485, uint8_t config)
Parameters:
  • rs485 – Type: RS485 *
  • config – Type: uint8_t, Range: See constants, Default: 3
Returns:
  • e_code – Type: int

Sets the communication LED configuration. By default the LED shows RS485 communication traffic by flickering.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is off.

The following constants are available for this function:

For config:

  • RS485_COMMUNICATION_LED_CONFIG_OFF = 0
  • RS485_COMMUNICATION_LED_CONFIG_ON = 1
  • RS485_COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
int rs485_get_communication_led_config(RS485 *rs485, uint8_t *ret_config)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_config – Type: uint8_t, Range: See constants, Default: 3
Returns:
  • e_code – Type: int

Returns the configuration as set by rs485_set_communication_led_config()

The following constants are available for this function:

For ret_config:

  • RS485_COMMUNICATION_LED_CONFIG_OFF = 0
  • RS485_COMMUNICATION_LED_CONFIG_ON = 1
  • RS485_COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
int rs485_set_error_led_config(RS485 *rs485, uint8_t config)
Parameters:
  • rs485 – Type: RS485 *
  • config – Type: uint8_t, Range: See constants, Default: 3
Returns:
  • e_code – Type: int

Sets the error LED configuration.

By default the error LED turns on if there is any error (see RS485_CALLBACK_ERROR_COUNT callback). If you call this function with the SHOW ERROR option again, the LED will turn off until the next error occurs.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is off.

The following constants are available for this function:

For config:

  • RS485_ERROR_LED_CONFIG_OFF = 0
  • RS485_ERROR_LED_CONFIG_ON = 1
  • RS485_ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_ERROR_LED_CONFIG_SHOW_ERROR = 3
int rs485_get_error_led_config(RS485 *rs485, uint8_t *ret_config)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_config – Type: uint8_t, Range: See constants, Default: 3
Returns:
  • e_code – Type: int

Returns the configuration as set by rs485_set_error_led_config().

The following constants are available for this function:

For ret_config:

  • RS485_ERROR_LED_CONFIG_OFF = 0
  • RS485_ERROR_LED_CONFIG_ON = 1
  • RS485_ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_ERROR_LED_CONFIG_SHOW_ERROR = 3
int rs485_set_buffer_config(RS485 *rs485, uint16_t send_buffer_size, uint16_t receive_buffer_size)
Parameters:
  • rs485 – Type: RS485 *
  • send_buffer_size – Type: uint16_t, Unit: 1 B, Range: [210 to 9216], Default: 5120
  • receive_buffer_size – Type: uint16_t, Unit: 1 B, Range: [210 to 9216], Default: 5120
Returns:
  • e_code – Type: int

Sets the send and receive buffer size in byte. In sum there is 10240 byte (10KiB) buffer available and the minimum buffer size is 1024 byte (1KiB) for both.

The current buffer content is lost if this function is called.

The send buffer holds data that was given by rs485_write() and could not be written yet. The receive buffer holds data that is received through RS485 but could not yet be send to the user, either by rs485_read() or through RS485_CALLBACK_READ callback.

int rs485_get_buffer_config(RS485 *rs485, uint16_t *ret_send_buffer_size, uint16_t *ret_receive_buffer_size)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_send_buffer_size – Type: uint16_t, Unit: 1 B, Range: [210 to 9216], Default: 5120
  • ret_receive_buffer_size – Type: uint16_t, Unit: 1 B, Range: [210 to 9216], Default: 5120
Returns:
  • e_code – Type: int

Returns the buffer configuration as set by rs485_set_buffer_config().

int rs485_get_buffer_status(RS485 *rs485, uint16_t *ret_send_buffer_used, uint16_t *ret_receive_buffer_used)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_send_buffer_used – Type: uint16_t, Unit: 1 B, Range: [0 to 9216]
  • ret_receive_buffer_used – Type: uint16_t, Unit: 1 B, Range: [0 to 9216]
Returns:
  • e_code – Type: int

Returns the currently used bytes for the send and received buffer.

See rs485_set_buffer_config() for buffer size configuration.

int rs485_get_error_count(RS485 *rs485, uint32_t *ret_overrun_error_count, uint32_t *ret_parity_error_count)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_overrun_error_count – Type: uint32_t, Range: [0 to 232 - 1]
  • ret_parity_error_count – Type: uint32_t, Range: [0 to 232 - 1]
Returns:
  • e_code – Type: int

Returns the current number of overrun and parity errors.

int rs485_get_modbus_common_error_count(RS485 *rs485, uint32_t *ret_timeout_error_count, uint32_t *ret_checksum_error_count, uint32_t *ret_frame_too_big_error_count, uint32_t *ret_illegal_function_error_count, uint32_t *ret_illegal_data_address_error_count, uint32_t *ret_illegal_data_value_error_count, uint32_t *ret_slave_device_failure_error_count)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_timeout_error_count – Type: uint32_t, Range: [0 to 232 - 1]
  • ret_checksum_error_count – Type: uint32_t, Range: [0 to 232 - 1]
  • ret_frame_too_big_error_count – Type: uint32_t, Range: [0 to 232 - 1]
  • ret_illegal_function_error_count – Type: uint32_t, Range: [0 to 232 - 1]
  • ret_illegal_data_address_error_count – Type: uint32_t, Range: [0 to 232 - 1]
  • ret_illegal_data_value_error_count – Type: uint32_t, Range: [0 to 232 - 1]
  • ret_slave_device_failure_error_count – Type: uint32_t, Range: [0 to 232 - 1]
Returns:
  • e_code – Type: int

Returns the current number of errors occurred in Modbus mode.

  • Timeout Error Count: Number of timeouts occurred.
  • Checksum Error Count: Number of failures due to Modbus frame CRC16 checksum mismatch.
  • Frame Too Big Error Count: Number of times frames were rejected because they exceeded maximum Modbus frame size which is 256 bytes.
  • Illegal Function Error Count: Number of errors when an unimplemented or illegal function is requested. This corresponds to Modbus exception code 1.
  • Illegal Data Address Error Count: Number of errors due to invalid data address. This corresponds to Modbus exception code 2.
  • Illegal Data Value Error Count: Number of errors due to invalid data value. This corresponds to Modbus exception code 3.
  • Slave Device Failure Error Count: Number of errors occurred on the slave device which were unrecoverable. This corresponds to Modbus exception code 4.
int rs485_modbus_slave_report_exception(RS485 *rs485, uint8_t request_id, int8_t exception_code)
Parameters:
  • rs485 – Type: RS485 *
  • request_id – Type: uint8_t, Range: [0 to 255]
  • exception_code – Type: int8_t, Range: See constants
Returns:
  • e_code – Type: int

In Modbus slave mode this function can be used to report a Modbus exception for a Modbus master request.

  • Request ID: Request ID of the request received by the slave.
  • Exception Code: Modbus exception code to report to the Modbus master.

The following constants are available for this function:

For exception_code:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
int rs485_modbus_slave_answer_read_coils_request(RS485 *rs485, uint8_t request_id, bool *coils, uint16_t coils_length)
Parameters:
  • rs485 – Type: RS485 *
  • request_id – Type: uint8_t, Range: [0 to 255]
  • coils – Type: bool *
  • coils_length – Type: uint16_t
Returns:
  • e_code – Type: int

In Modbus slave mode this function can be used to answer a master request to read coils.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Coils: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the RS485_CALLBACK_MODBUS_SLAVE_READ_COILS_REQUEST callback with the Request ID as provided by the argument of the callback.

int rs485_modbus_master_read_coils(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, uint16_t count, uint8_t *ret_request_id)
Parameters:
  • rs485 – Type: RS485 *
  • slave_address – Type: uint8_t, Range: [0 to 247]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • count – Type: uint16_t, Range: [1 to 2000]
Output Parameters:
  • ret_request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus master mode this function can be used to read coils from a slave. This function creates a Modbus function code 1 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first coil to read. For backwards compatibility reasons this parameter is called Starting Address. It is not an address, but instead a coil number in the range of 1 to 65536.
  • Count: Number of coils to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the RS485_CALLBACK_MODBUS_MASTER_READ_COILS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

int rs485_modbus_slave_answer_read_holding_registers_request(RS485 *rs485, uint8_t request_id, uint16_t *holding_registers, uint16_t holding_registers_length)
Parameters:
  • rs485 – Type: RS485 *
  • request_id – Type: uint8_t, Range: [0 to 255]
  • holding_registers – Type: uint16_t *, Range: [0 to 216 - 1]
  • holding_registers_length – Type: uint16_t
Returns:
  • e_code – Type: int

In Modbus slave mode this function can be used to answer a master request to read holding registers.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Holding Registers: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the RS485_CALLBACK_MODBUS_SLAVE_READ_HOLDING_REGISTERS_REQUEST callback with the Request ID as provided by the argument of the callback.

int rs485_modbus_master_read_holding_registers(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, uint16_t count, uint8_t *ret_request_id)
Parameters:
  • rs485 – Type: RS485 *
  • slave_address – Type: uint8_t, Range: [0 to 247]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • count – Type: uint16_t, Range: [1 to 125]
Output Parameters:
  • ret_request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus master mode this function can be used to read holding registers from a slave. This function creates a Modbus function code 3 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first holding register to read. For backwards compatibility reasons this parameter is called Starting Address. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is implicit and must be omitted.
  • Count: Number of holding registers to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the RS485_CALLBACK_MODBUS_MASTER_READ_HOLDING_REGISTERS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

int rs485_modbus_slave_answer_write_single_coil_request(RS485 *rs485, uint8_t request_id)
Parameters:
  • rs485 – Type: RS485 *
  • request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus slave mode this function can be used to answer a master request to write a single coil.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the RS485_CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_COIL_REQUEST callback with the Request ID as provided by the arguments of the callback.

int rs485_modbus_master_write_single_coil(RS485 *rs485, uint8_t slave_address, uint32_t coil_address, bool coil_value, uint8_t *ret_request_id)
Parameters:
  • rs485 – Type: RS485 *
  • slave_address – Type: uint8_t, Range: [0 to 247]
  • coil_address – Type: uint32_t, Range: [1 to 216]
  • coil_value – Type: bool
Output Parameters:
  • ret_request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus master mode this function can be used to write a single coil of a slave. This function creates a Modbus function code 5 request.

  • Slave Address: Address of the target Modbus slave.
  • Coil Address: Number of the coil to be written. For backwards compatibility reasons, this parameter is called Starting Address. It is not an address, but instead a coil number in the range of 1 to 65536.
  • Coil Value: Value to be written.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the RS485_CALLBACK_MODBUS_MASTER_WRITE_SINGLE_COIL_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

int rs485_modbus_slave_answer_write_single_register_request(RS485 *rs485, uint8_t request_id)
Parameters:
  • rs485 – Type: RS485 *
  • request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus slave mode this function can be used to answer a master request to write a single register.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the RS485_CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_REGISTER_REQUEST callback with the Request ID, Register Address and Register Value as provided by the arguments of the callback.

int rs485_modbus_master_write_single_register(RS485 *rs485, uint8_t slave_address, uint32_t register_address, uint16_t register_value, uint8_t *ret_request_id)
Parameters:
  • rs485 – Type: RS485 *
  • slave_address – Type: uint8_t, Range: [0 to 247]
  • register_address – Type: uint32_t, Range: [1 to 216]
  • register_value – Type: uint16_t, Range: [0 to 216 - 1]
Output Parameters:
  • ret_request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus master mode this function can be used to write a single holding register of a slave. This function creates a Modbus function code 6 request.

  • Slave Address: Address of the target Modbus slave.
  • Register Address: Number of the holding register to be written. For backwards compatibility reasons, this parameter is called Starting Address. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is implicit and must be omitted.
  • Register Value: Value to be written.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the RS485_CALLBACK_MODBUS_MASTER_WRITE_SINGLE_REGISTER_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

int rs485_modbus_slave_answer_write_multiple_coils_request(RS485 *rs485, uint8_t request_id)
Parameters:
  • rs485 – Type: RS485 *
  • request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus slave mode this function can be used to answer a master request to write multiple coils.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the RS485_CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_COILS_REQUEST callback with the Request ID of the callback.

int rs485_modbus_master_write_multiple_coils(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, bool *coils, uint16_t coils_length, uint8_t *ret_request_id)
Parameters:
  • rs485 – Type: RS485 *
  • slave_address – Type: uint8_t, Range: [0 to 247]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • coils – Type: bool *
  • coils_length – Type: uint16_t
Output Parameters:
  • ret_request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus master mode this function can be used to write multiple coils of a slave. This function creates a Modbus function code 15 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first coil to write. For backwards compatibility reasons, this parameter is called Starting Address.It is not an address, but instead a coil number in the range of 1 to 65536.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the RS485_CALLBACK_MODBUS_MASTER_WRITE_MULTIPLE_COILS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

int rs485_modbus_slave_answer_write_multiple_registers_request(RS485 *rs485, uint8_t request_id)
Parameters:
  • rs485 – Type: RS485 *
  • request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus slave mode this function can be used to answer a master request to write multiple registers.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the RS485_CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_REGISTERS_REQUEST callback with the Request ID of the callback.

int rs485_modbus_master_write_multiple_registers(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, uint16_t *registers, uint16_t registers_length, uint8_t *ret_request_id)
Parameters:
  • rs485 – Type: RS485 *
  • slave_address – Type: uint8_t, Range: [0 to 247]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • registers – Type: uint16_t *, Range: [0 to 216 - 1]
  • registers_length – Type: uint16_t
Output Parameters:
  • ret_request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus master mode this function can be used to write multiple registers of a slave. This function creates a Modbus function code 16 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first holding register to write. For backwards compatibility reasons, this parameter is called Starting Address. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is implicit and must be omitted.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the RS485_CALLBACK_MODBUS_MASTER_WRITE_MULTIPLE_REGISTERS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

int rs485_modbus_slave_answer_read_discrete_inputs_request(RS485 *rs485, uint8_t request_id, bool *discrete_inputs, uint16_t discrete_inputs_length)
Parameters:
  • rs485 – Type: RS485 *
  • request_id – Type: uint8_t, Range: [0 to 255]
  • discrete_inputs – Type: bool *
  • discrete_inputs_length – Type: uint16_t
Returns:
  • e_code – Type: int

In Modbus slave mode this function can be used to answer a master request to read discrete inputs.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Discrete Inputs: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the RS485_CALLBACK_MODBUS_SLAVE_READ_DISCRETE_INPUTS_REQUEST callback with the Request ID as provided by the argument of the callback.

int rs485_modbus_master_read_discrete_inputs(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, uint16_t count, uint8_t *ret_request_id)
Parameters:
  • rs485 – Type: RS485 *
  • slave_address – Type: uint8_t, Range: [0 to 247]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • count – Type: uint16_t, Range: [1 to 2000]
Output Parameters:
  • ret_request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus master mode this function can be used to read discrete inputs from a slave. This function creates a Modbus function code 2 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first discrete input to read. For backwards compatibility reasons, this parameter is called Starting Address. It is not an address, but instead a discrete input number in the range of 1 to 65536. The prefix digit 1 (for discrete input) is implicit and must be omitted.
  • Count: Number of discrete inputs to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the RS485_CALLBACK_MODBUS_MASTER_READ_DISCRETE_INPUTS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

int rs485_modbus_slave_answer_read_input_registers_request(RS485 *rs485, uint8_t request_id, uint16_t *input_registers, uint16_t input_registers_length)
Parameters:
  • rs485 – Type: RS485 *
  • request_id – Type: uint8_t, Range: [0 to 255]
  • input_registers – Type: uint16_t *, Range: [0 to 216 - 1]
  • input_registers_length – Type: uint16_t
Returns:
  • e_code – Type: int

In Modbus slave mode this function can be used to answer a master request to read input registers.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Input Registers: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the RS485_CALLBACK_MODBUS_SLAVE_READ_INPUT_REGISTERS_REQUEST callback with the Request ID as provided by the argument of the callback.

int rs485_modbus_master_read_input_registers(RS485 *rs485, uint8_t slave_address, uint32_t starting_address, uint16_t count, uint8_t *ret_request_id)
Parameters:
  • rs485 – Type: RS485 *
  • slave_address – Type: uint8_t, Range: [0 to 247]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • count – Type: uint16_t, Range: [1 to 125]
Output Parameters:
  • ret_request_id – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

In Modbus master mode this function can be used to read input registers from a slave. This function creates a Modbus function code 4 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Number of the first input register to read. For backwards compatibility reasons, this parameter is called Starting Address. It is not an address, but instead an input register number in the range of 1 to 65536. The prefix digit 3 (for input register) is implicit and must be omitted.
  • Count: Number of input registers to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the RS485_CALLBACK_MODBUS_MASTER_READ_INPUT_REGISTERS_RESPONSE callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

int rs485_get_spitfp_error_count(RS485 *rs485, uint32_t *ret_error_count_ack_checksum, uint32_t *ret_error_count_message_checksum, uint32_t *ret_error_count_frame, uint32_t *ret_error_count_overflow)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_error_count_ack_checksum – Type: uint32_t, Range: [0 to 232 - 1]
  • ret_error_count_message_checksum – Type: uint32_t, Range: [0 to 232 - 1]
  • ret_error_count_frame – Type: uint32_t, Range: [0 to 232 - 1]
  • ret_error_count_overflow – Type: uint32_t, Range: [0 to 232 - 1]
Returns:
  • e_code – Type: int

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

int rs485_set_status_led_config(RS485 *rs485, uint8_t config)
Parameters:
  • rs485 – Type: RS485 *
  • config – Type: uint8_t, Range: See constants, Default: 3
Returns:
  • e_code – Type: int

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

For config:

  • RS485_STATUS_LED_CONFIG_OFF = 0
  • RS485_STATUS_LED_CONFIG_ON = 1
  • RS485_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_STATUS_LED_CONFIG_SHOW_STATUS = 3
int rs485_get_status_led_config(RS485 *rs485, uint8_t *ret_config)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_config – Type: uint8_t, Range: See constants, Default: 3
Returns:
  • e_code – Type: int

Returns the configuration as set by rs485_set_status_led_config()

The following constants are available for this function:

For ret_config:

  • RS485_STATUS_LED_CONFIG_OFF = 0
  • RS485_STATUS_LED_CONFIG_ON = 1
  • RS485_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS485_STATUS_LED_CONFIG_SHOW_STATUS = 3
int rs485_get_chip_temperature(RS485 *rs485, int16_t *ret_temperature)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_temperature – Type: int16_t, Unit: 1 °C, Range: [-215 to 215 - 1]
Returns:
  • e_code – Type: int

Returns the temperature as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

int rs485_reset(RS485 *rs485)
Parameters:
  • rs485 – Type: RS485 *
Returns:
  • e_code – Type: int

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

int rs485_get_identity(RS485 *rs485, char ret_uid[8], char ret_connected_uid[8], char *ret_position, uint8_t ret_hardware_version[3], uint8_t ret_firmware_version[3], uint16_t *ret_device_identifier)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_uid – Type: char[8]
  • ret_connected_uid – Type: char[8]
  • ret_position – Type: char, Range: ['a' to 'h', 'z']
  • ret_hardware_version – Type: uint8_t[3]
    • 0: major – Type: uint8_t, Range: [0 to 255]
    • 1: minor – Type: uint8_t, Range: [0 to 255]
    • 2: revision – Type: uint8_t, Range: [0 to 255]
  • ret_firmware_version – Type: uint8_t[3]
    • 0: major – Type: uint8_t, Range: [0 to 255]
    • 1: minor – Type: uint8_t, Range: [0 to 255]
    • 2: revision – Type: uint8_t, Range: [0 to 255]
  • ret_device_identifier – Type: uint16_t, Range: [0 to 216 - 1]
Returns:
  • e_code – Type: int

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions

void rs485_register_callback(RS485 *rs485, int16_t callback_id, void (*function)(void), void *user_data)
Parameters:
  • rs485 – Type: RS485 *
  • callback_id – Type: int16_t
  • function – Type: void (*)(void)
  • user_data – Type: void *

Registers the given function with the given callback_id. The user_data will be passed as the last parameter to the function.

The available callback IDs with corresponding function signatures are listed below.

int rs485_enable_read_callback(RS485 *rs485)
Parameters:
  • rs485 – Type: RS485 *
Returns:
  • e_code – Type: int

Enables the RS485_CALLBACK_READ callback. This will disable the RS485_CALLBACK_FRAME_READABLE callback.

By default the callback is disabled.

int rs485_disable_read_callback(RS485 *rs485)
Parameters:
  • rs485 – Type: RS485 *
Returns:
  • e_code – Type: int

Disables the RS485_CALLBACK_READ callback.

By default the callback is disabled.

int rs485_is_read_callback_enabled(RS485 *rs485, bool *ret_enabled)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_enabled – Type: bool, Default: false
Returns:
  • e_code – Type: int

Returns true if the RS485_CALLBACK_READ callback is enabled, false otherwise.

int rs485_enable_error_count_callback(RS485 *rs485)
Parameters:
  • rs485 – Type: RS485 *
Returns:
  • e_code – Type: int

Enables the RS485_CALLBACK_ERROR_COUNT callback.

By default the callback is disabled.

int rs485_disable_error_count_callback(RS485 *rs485)
Parameters:
  • rs485 – Type: RS485 *
Returns:
  • e_code – Type: int

Disables the RS485_CALLBACK_ERROR_COUNT callback.

By default the callback is disabled.

int rs485_is_error_count_callback_enabled(RS485 *rs485, bool *ret_enabled)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_enabled – Type: bool, Default: true
Returns:
  • e_code – Type: int

Returns true if the RS485_CALLBACK_ERROR_COUNT callback is enabled, false otherwise.

int rs485_set_frame_readable_callback_configuration(RS485 *rs485, uint16_t frame_size)
Parameters:
  • rs485 – Type: RS485 *
  • frame_size – Type: uint16_t, Unit: 1 B, Range: [0 to 9216], Default: 0
Returns:
  • e_code – Type: int

Configures the RS485_CALLBACK_FRAME_READABLE callback. The frame size is the number of bytes, that have to be readable to trigger the callback. A frame size of 0 disables the callback. A frame size greater than 0 enables the callback and disables the RS485_CALLBACK_READ callback.

By default the callback is disabled.

New in version 2.0.5 (Plugin).

int rs485_get_frame_readable_callback_configuration(RS485 *rs485, uint16_t *ret_frame_size)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_frame_size – Type: uint16_t, Unit: 1 B, Range: [0 to 9216], Default: 0
Returns:
  • e_code – Type: int

Returns the callback configuration as set by rs485_set_frame_readable_callback_configuration().

New in version 2.0.5 (Plugin).

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the rs485_register_callback() function:

void my_callback(int value, void *user_data) {
    printf("Value: %d\n", value);
}

rs485_register_callback(&rs485,
                        RS485_CALLBACK_EXAMPLE,
                        (void (*)(void))my_callback,
                        NULL);

The available constants with corresponding function signatures are described below.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

RS485_CALLBACK_READ
void callback(char *message, uint16_t message_length, void *user_data)
Callback Parameters:
  • message – Type: char *
  • message_length – Type: uint16_t
  • user_data – Type: void *

This callback is called if new data is available.

To enable this callback, use rs485_enable_read_callback().

Note

If reconstructing the value fails, the callback is triggered with NULL for message.

RS485_CALLBACK_ERROR_COUNT
void callback(uint32_t overrun_error_count, uint32_t parity_error_count, void *user_data)
Callback Parameters:
  • overrun_error_count – Type: uint32_t, Range: [0 to 232 - 1]
  • parity_error_count – Type: uint32_t, Range: [0 to 232 - 1]
  • user_data – Type: void *

This callback is called if a new error occurs. It returns the current overrun and parity error count.

RS485_CALLBACK_MODBUS_SLAVE_READ_COILS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, uint16_t count, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • count – Type: uint16_t, Range: [1 to 2000]
  • user_data – Type: void *

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read coils. The parameters are request ID of the request, the number of the first coil to be read and the number of coils to be read as received by the request. The number of the first coil is called starting address for backwards compatibility reasons. It is not an address, but instead a coil number in the range of 1 to 65536.

To send a response of this request use rs485_modbus_slave_answer_read_coils_request().

RS485_CALLBACK_MODBUS_MASTER_READ_COILS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, bool *coils, uint16_t coils_length, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • exception_code – Type: int8_t, Range: See constants
  • coils – Type: bool *
  • coils_length – Type: uint16_t
  • user_data – Type: void *

This callback is called only in Modbus master mode when the master receives a valid response of a request to read coils.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by rs485_set_modbus_configuration().

Note

If reconstructing the value fails, the callback is triggered with NULL for coils.

The following constants are available for this function:

For exception_code:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_READ_HOLDING_REGISTERS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, uint16_t count, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • count – Type: uint16_t, Range: [1 to 125]
  • user_data – Type: void *

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read holding registers. The parameters are request ID of the request, the number of the first holding register to be read and the number of holding registers to be read as received by the request. The number of the first holding register is called starting address for backwards compatibility reasons. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is omitted.

To send a response of this request use rs485_modbus_slave_answer_read_holding_registers_request().

RS485_CALLBACK_MODBUS_MASTER_READ_HOLDING_REGISTERS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, uint16_t *holding_registers, uint16_t holding_registers_length, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • exception_code – Type: int8_t, Range: See constants
  • holding_registers – Type: uint16_t *, Range: [0 to 216 - 1]
  • holding_registers_length – Type: uint16_t
  • user_data – Type: void *

This callback is called only in Modbus master mode when the master receives a valid response of a request to read holding registers.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by rs485_set_modbus_configuration().

Note

If reconstructing the value fails, the callback is triggered with NULL for holding_registers.

The following constants are available for this function:

For exception_code:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_COIL_REQUEST
void callback(uint8_t request_id, uint32_t coil_address, bool coil_value, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • coil_address – Type: uint32_t, Range: [1 to 216]
  • coil_value – Type: bool
  • user_data – Type: void *

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write a single coil. The parameters are request ID of the request, the number of the coil and the value of coil to be written as received by the request. The number of the coil is called coil address for backwards compatibility reasons. It is not an address, but instead a coil number in the range of 1 to 65536.

To send a response of this request use rs485_modbus_slave_answer_write_single_coil_request().

RS485_CALLBACK_MODBUS_MASTER_WRITE_SINGLE_COIL_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • exception_code – Type: int8_t, Range: See constants
  • user_data – Type: void *

This callback is called only in Modbus master mode when the master receives a valid response of a request to write a single coil.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by rs485_set_modbus_configuration().

The following constants are available for this function:

For exception_code:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_WRITE_SINGLE_REGISTER_REQUEST
void callback(uint8_t request_id, uint32_t register_address, uint16_t register_value, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • register_address – Type: uint32_t, Range: [1 to 216]
  • register_value – Type: uint16_t, Range: [0 to 216 - 1]
  • user_data – Type: void *

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write a single holding register. The parameters are request ID of the request, the number of the holding register and the register value to be written as received by the request. The number of the holding register is called starting address for backwards compatibility reasons. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is omitted.

To send a response of this request use rs485_modbus_slave_answer_write_single_register_request().

RS485_CALLBACK_MODBUS_MASTER_WRITE_SINGLE_REGISTER_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • exception_code – Type: int8_t, Range: See constants
  • user_data – Type: void *

This callback is called only in Modbus master mode when the master receives a valid response of a request to write a single register.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by rs485_set_modbus_configuration().

The following constants are available for this function:

For exception_code:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_COILS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, bool *coils, uint16_t coils_length, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • coils – Type: bool *
  • coils_length – Type: uint16_t
  • user_data – Type: void *

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write multiple coils. The parameters are request ID of the request, the number of the first coil and the data to be written as received by the request. The number of the first coil is called starting address for backwards compatibility reasons. It is not an address, but instead a coil number in the range of 1 to 65536.

To send a response of this request use rs485_modbus_slave_answer_write_multiple_coils_request().

Note

If reconstructing the value fails, the callback is triggered with NULL for coils.

RS485_CALLBACK_MODBUS_MASTER_WRITE_MULTIPLE_COILS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • exception_code – Type: int8_t, Range: See constants
  • user_data – Type: void *

This callback is called only in Modbus master mode when the master receives a valid response of a request to read coils.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by rs485_set_modbus_configuration().

The following constants are available for this function:

For exception_code:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_WRITE_MULTIPLE_REGISTERS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, uint16_t *registers, uint16_t registers_length, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • registers – Type: uint16_t *, Range: [0 to 216 - 1]
  • registers_length – Type: uint16_t
  • user_data – Type: void *

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write multiple holding registers. The parameters are request ID of the request, the number of the first holding register and the data to be written as received by the request. The number of the first holding register is called starting address for backwards compatibility reasons. It is not an address, but instead a holding register number in the range of 1 to 65536. The prefix digit 4 (for holding register) is omitted.

To send a response of this request use rs485_modbus_slave_answer_write_multiple_registers_request().

Note

If reconstructing the value fails, the callback is triggered with NULL for registers.

RS485_CALLBACK_MODBUS_MASTER_WRITE_MULTIPLE_REGISTERS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • exception_code – Type: int8_t, Range: See constants
  • user_data – Type: void *

This callback is called only in Modbus master mode when the master receives a valid response of a request to write multiple registers.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by rs485_set_modbus_configuration().

The following constants are available for this function:

For exception_code:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_READ_DISCRETE_INPUTS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, uint16_t count, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • count – Type: uint16_t, Range: [1 to 2000]
  • user_data – Type: void *

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read discrete inputs. The parameters are request ID of the request, the number of the first discrete input and the number of discrete inputs to be read as received by the request. The number of the first discrete input is called starting address for backwards compatibility reasons. It is not an address, but instead a discrete input number in the range of 1 to 65536. The prefix digit 1 (for discrete input) is omitted.

To send a response of this request use rs485_modbus_slave_answer_read_discrete_inputs_request().

RS485_CALLBACK_MODBUS_MASTER_READ_DISCRETE_INPUTS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, bool *discrete_inputs, uint16_t discrete_inputs_length, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • exception_code – Type: int8_t, Range: See constants
  • discrete_inputs – Type: bool *
  • discrete_inputs_length – Type: uint16_t
  • user_data – Type: void *

This callback is called only in Modbus master mode when the master receives a valid response of a request to read discrete inputs.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by rs485_set_modbus_configuration().

Note

If reconstructing the value fails, the callback is triggered with NULL for discrete_inputs.

The following constants are available for this function:

For exception_code:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_MODBUS_SLAVE_READ_INPUT_REGISTERS_REQUEST
void callback(uint8_t request_id, uint32_t starting_address, uint16_t count, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • starting_address – Type: uint32_t, Range: [1 to 216]
  • count – Type: uint16_t, Range: [1 to 125]
  • user_data – Type: void *

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read input registers. The parameters are request ID of the request, the number of the first input register and the number of input registers to be read as received by the request. The number of the first input register is called starting address for backwards compatibility reasons. It is not an address, but instead a input register number in the range of 1 to 65536. The prefix digit 3 (for input register) is omitted.

To send a response of this request use rs485_modbus_slave_answer_read_input_registers_request().

RS485_CALLBACK_MODBUS_MASTER_READ_INPUT_REGISTERS_RESPONSE
void callback(uint8_t request_id, int8_t exception_code, uint16_t *input_registers, uint16_t input_registers_length, void *user_data)
Callback Parameters:
  • request_id – Type: uint8_t, Range: [0 to 255]
  • exception_code – Type: int8_t, Range: See constants
  • input_registers – Type: uint16_t *, Range: [0 to 216 - 1]
  • input_registers_length – Type: uint16_t
  • user_data – Type: void *

This callback is called only in Modbus master mode when the master receives a valid response of a request to read input registers.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than 0 then the number represents a Modbus exception code. If it is less than 0 then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by rs485_set_modbus_configuration().

Note

If reconstructing the value fails, the callback is triggered with NULL for input_registers.

The following constants are available for this function:

For exception_code:

  • RS485_EXCEPTION_CODE_TIMEOUT = -1
  • RS485_EXCEPTION_CODE_SUCCESS = 0
  • RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
RS485_CALLBACK_FRAME_READABLE
void callback(uint16_t frame_count, void *user_data)
Callback Parameters:
  • frame_count – Type: uint16_t, Range: [0 to 216 - 1]
  • user_data – Type: void *

This callback is called if at least one frame of data is readable. The frame size is configured with rs485_set_frame_readable_callback_configuration(). The frame count parameter is the number of frames that can be read. This callback is triggered only once until rs485_read() is called. This means, that if you have configured a frame size of X bytes, you can read exactly X bytes using the rs485_read() function, every time the callback triggers without checking the frame count parameter.

New in version 2.0.5 (Plugin).

Virtual Functions

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

int rs485_get_api_version(RS485 *rs485, uint8_t ret_api_version[3])
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_api_version – Type: uint8_t[3]
    • 0: major – Type: uint8_t, Range: [0 to 255]
    • 1: minor – Type: uint8_t, Range: [0 to 255]
    • 2: revision – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

Returns the version of the API definition implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

int rs485_get_response_expected(RS485 *rs485, uint8_t function_id, bool *ret_response_expected)
Parameters:
  • rs485 – Type: RS485 *
  • function_id – Type: uint8_t, Range: See constants
Output Parameters:
  • ret_response_expected – Type: bool
Returns:
  • e_code – Type: int

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by rs485_set_response_expected(). For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • RS485_FUNCTION_ENABLE_READ_CALLBACK = 3
  • RS485_FUNCTION_DISABLE_READ_CALLBACK = 4
  • RS485_FUNCTION_SET_RS485_CONFIGURATION = 6
  • RS485_FUNCTION_SET_MODBUS_CONFIGURATION = 8
  • RS485_FUNCTION_SET_MODE = 10
  • RS485_FUNCTION_SET_COMMUNICATION_LED_CONFIG = 12
  • RS485_FUNCTION_SET_ERROR_LED_CONFIG = 14
  • RS485_FUNCTION_SET_BUFFER_CONFIG = 16
  • RS485_FUNCTION_ENABLE_ERROR_COUNT_CALLBACK = 19
  • RS485_FUNCTION_DISABLE_ERROR_COUNT_CALLBACK = 20
  • RS485_FUNCTION_MODBUS_SLAVE_REPORT_EXCEPTION = 24
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_COILS_REQUEST = 25
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_HOLDING_REGISTERS_REQUEST = 27
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_COIL_REQUEST = 29
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_REGISTER_REQUEST = 31
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_COILS_REQUEST = 33
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_REGISTERS_REQUEST = 35
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_DISCRETE_INPUTS_REQUEST = 37
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_INPUT_REGISTERS_REQUEST = 39
  • RS485_FUNCTION_SET_FRAME_READABLE_CALLBACK_CONFIGURATION = 59
  • RS485_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • RS485_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • RS485_FUNCTION_RESET = 243
  • RS485_FUNCTION_WRITE_UID = 248
int rs485_set_response_expected(RS485 *rs485, uint8_t function_id, bool response_expected)
Parameters:
  • rs485 – Type: RS485 *
  • function_id – Type: uint8_t, Range: See constants
  • response_expected – Type: bool
Returns:
  • e_code – Type: int

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • RS485_FUNCTION_ENABLE_READ_CALLBACK = 3
  • RS485_FUNCTION_DISABLE_READ_CALLBACK = 4
  • RS485_FUNCTION_SET_RS485_CONFIGURATION = 6
  • RS485_FUNCTION_SET_MODBUS_CONFIGURATION = 8
  • RS485_FUNCTION_SET_MODE = 10
  • RS485_FUNCTION_SET_COMMUNICATION_LED_CONFIG = 12
  • RS485_FUNCTION_SET_ERROR_LED_CONFIG = 14
  • RS485_FUNCTION_SET_BUFFER_CONFIG = 16
  • RS485_FUNCTION_ENABLE_ERROR_COUNT_CALLBACK = 19
  • RS485_FUNCTION_DISABLE_ERROR_COUNT_CALLBACK = 20
  • RS485_FUNCTION_MODBUS_SLAVE_REPORT_EXCEPTION = 24
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_COILS_REQUEST = 25
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_HOLDING_REGISTERS_REQUEST = 27
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_COIL_REQUEST = 29
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_REGISTER_REQUEST = 31
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_COILS_REQUEST = 33
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_REGISTERS_REQUEST = 35
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_DISCRETE_INPUTS_REQUEST = 37
  • RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_INPUT_REGISTERS_REQUEST = 39
  • RS485_FUNCTION_SET_FRAME_READABLE_CALLBACK_CONFIGURATION = 59
  • RS485_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • RS485_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • RS485_FUNCTION_RESET = 243
  • RS485_FUNCTION_WRITE_UID = 248
int rs485_set_response_expected_all(RS485 *rs485, bool response_expected)
Parameters:
  • rs485 – Type: RS485 *
  • response_expected – Type: bool
Returns:
  • e_code – Type: int

Changes the response expected flag for all setter and callback configuration functions of this device at once.

Internal Functions

Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.

int rs485_set_bootloader_mode(RS485 *rs485, uint8_t mode, uint8_t *ret_status)
Parameters:
  • rs485 – Type: RS485 *
  • mode – Type: uint8_t, Range: See constants
Output Parameters:
  • ret_status – Type: uint8_t, Range: See constants
Returns:
  • e_code – Type: int

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

For mode:

  • RS485_BOOTLOADER_MODE_BOOTLOADER = 0
  • RS485_BOOTLOADER_MODE_FIRMWARE = 1
  • RS485_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4

For ret_status:

  • RS485_BOOTLOADER_STATUS_OK = 0
  • RS485_BOOTLOADER_STATUS_INVALID_MODE = 1
  • RS485_BOOTLOADER_STATUS_NO_CHANGE = 2
  • RS485_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • RS485_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • RS485_BOOTLOADER_STATUS_CRC_MISMATCH = 5
int rs485_get_bootloader_mode(RS485 *rs485, uint8_t *ret_mode)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_mode – Type: uint8_t, Range: See constants
Returns:
  • e_code – Type: int

Returns the current bootloader mode, see rs485_set_bootloader_mode().

The following constants are available for this function:

For ret_mode:

  • RS485_BOOTLOADER_MODE_BOOTLOADER = 0
  • RS485_BOOTLOADER_MODE_FIRMWARE = 1
  • RS485_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
int rs485_set_write_firmware_pointer(RS485 *rs485, uint32_t pointer)
Parameters:
  • rs485 – Type: RS485 *
  • pointer – Type: uint32_t, Unit: 1 B, Range: [0 to 232 - 1]
Returns:
  • e_code – Type: int

Sets the firmware pointer for rs485_write_firmware(). The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

int rs485_write_firmware(RS485 *rs485, uint8_t data[64], uint8_t *ret_status)
Parameters:
  • rs485 – Type: RS485 *
  • data – Type: uint8_t[64], Range: [0 to 255]
Output Parameters:
  • ret_status – Type: uint8_t, Range: [0 to 255]
Returns:
  • e_code – Type: int

Writes 64 Bytes of firmware at the position as written by rs485_set_write_firmware_pointer() before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

int rs485_write_uid(RS485 *rs485, uint32_t uid)
Parameters:
  • rs485 – Type: RS485 *
  • uid – Type: uint32_t, Range: [0 to 232 - 1]
Returns:
  • e_code – Type: int

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

int rs485_read_uid(RS485 *rs485, uint32_t *ret_uid)
Parameters:
  • rs485 – Type: RS485 *
Output Parameters:
  • ret_uid – Type: uint32_t, Range: [0 to 232 - 1]
Returns:
  • e_code – Type: int

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

Constants

RS485_DEVICE_IDENTIFIER

This constant is used to identify a RS485 Bricklet.

The rs485_get_identity() function and the IPCON_CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

RS485_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a RS485 Bricklet.