Specifications / Modbus Protocol / API / Bricklets (Discontinued) / Thermocouple Bricklet

Modbus - Thermocouple Bricklet¶

This is the description of the Modbus protocol for the Thermocouple Bricklet. General information and technical specifications for the Thermocouple Bricklet are summarized in its hardware description.

API¶

A general description of the Modbus protocol structure can be found here.

Basic Functions¶

BrickletThermocouple.get_temperature¶

Function ID:	1
Request:	empty payload
Response:	temperature – Type: int32, Unit: 1/100 °C, Range: [-21000 to 180000]

Returns the temperature of the thermocouple.

If you want to get the temperature periodically, it is recommended to use the CALLBACK_TEMPERATURE callback and set the period with set_temperature_callback_period.

Advanced Functions¶

BrickletThermocouple.set_configuration¶

Function ID:	10
Request:	averaging – Type: uint8, Range: See meanings, Default: 16 thermocouple_type – Type: uint8, Range: See meanings, Default: 3 filter – Type: uint8, Range: See meanings, Default: 0
Response:	no response

You can configure averaging size, thermocouple type and frequency filtering.

Available averaging sizes are 1, 2, 4, 8 and 16 samples.

As thermocouple type you can use B, E, J, K, N, R, S and T. If you have a different thermocouple or a custom thermocouple you can also use G8 and G32. With these types the returned value will not be in °C/100, it will be calculated by the following formulas:

G8: value = 8 * 1.6 * 2^17 * Vin
G32: value = 32 * 1.6 * 2^17 * Vin

where Vin is the thermocouple input voltage.

The frequency filter can be either configured to 50Hz or to 60Hz. You should configure it according to your utility frequency.

The conversion time depends on the averaging and filter configuration, it can be calculated as follows:

60Hz: time = 82 + (samples - 1) * 16.67
50Hz: time = 98 + (samples - 1) * 20

The following meanings are defined for the elements of this function:

For averaging:

1 = 1
2 = 2
4 = 4
8 = 8
16 = 16

For thermocouple_type:

0 = B
1 = E
2 = J
3 = K
4 = N
5 = R
6 = S
7 = T
8 = G8
9 = G32

For filter:

0 = 50Hz
1 = 60Hz

BrickletThermocouple.get_configuration¶

Function ID:	11
Request:	empty payload
Response:	averaging – Type: uint8, Range: See meanings, Default: 16 thermocouple_type – Type: uint8, Range: See meanings, Default: 3 filter – Type: uint8, Range: See meanings, Default: 0

Returns the configuration as set by set_configuration.

The following meanings are defined for the elements of this function:

For averaging:

1 = 1
2 = 2
4 = 4
8 = 8
16 = 16

For thermocouple_type:

0 = B
1 = E
2 = J
3 = K
4 = N
5 = R
6 = S
7 = T
8 = G8
9 = G32

For filter:

0 = 50Hz
1 = 60Hz

BrickletThermocouple.get_error_state¶

Function ID:	12
Request:	empty payload
Response:	over_under – Type: bool open_circuit – Type: bool

Returns the current error state. There are two possible errors:

Over/Under Voltage and
Open Circuit.

Over/Under Voltage happens for voltages below 0V or above 3.3V. In this case it is very likely that your thermocouple is defective. An Open Circuit error indicates that there is no thermocouple connected.

You can use the CALLBACK_ERROR_STATE callback to automatically get triggered when the error state changes.

BrickletThermocouple.get_identity¶

Function ID:	255
Request:	empty payload
Response:	uid – Type: char[8] connected_uid – Type: char[8] position – Type: char, Range: ['a' to 'h', 'z'] hardware_version – Type: uint8[3] 0: major – Type: uint8, Range: [0 to 255] 1: minor – Type: uint8, Range: [0 to 255] 2: revision – Type: uint8, Range: [0 to 255] firmware_version – Type: uint8[3] 0: major – Type: uint8, Range: [0 to 255] 1: minor – Type: uint8, Range: [0 to 255] 2: revision – Type: uint8, Range: [0 to 255] device_identifier – Type: uint16, Range: [0 to 2¹⁶ - 1]

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.

Callback Configuration Functions¶

BrickletThermocouple.set_temperature_callback_period¶

Function ID:	2
Request:	period – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0
Response:	no response

Sets the period with which the CALLBACK_TEMPERATURE callback is triggered periodically. A value of 0 turns the callback off.

The CALLBACK_TEMPERATURE callback is only triggered if the temperature has changed since the last triggering.

BrickletThermocouple.get_temperature_callback_period¶

Function ID:	3
Request:	empty payload
Response:	period – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0

Returns the period as set by set_temperature_callback_period.

BrickletThermocouple.set_temperature_callback_threshold¶

Function ID:	4
Request:	option – Type: char, Range: See meanings, Default: 'x' min – Type: int32, Unit: 1/100 °C, Range: [-2³¹ to 2³¹ - 1], Default: 0 max – Type: int32, Unit: 1/100 °C, Range: [-2³¹ to 2³¹ - 1], Default: 0
Response:	no response

Sets the thresholds for the CALLBACK_TEMPERATURE_REACHED callback.

The following options are possible:

Option	Description
'x'	Callback is turned off
'o'	Callback is triggered when the temperature is outside the min and max values
'i'	Callback is triggered when the temperature is inside the min and max values
'<'	Callback is triggered when the temperature is smaller than the min value (max is ignored)
'>'	Callback is triggered when the temperature is greater than the min value (max is ignored)

The following meanings are defined for the elements of this function:

For option:

'x' = Off
'o' = Outside
'i' = Inside
'<' = Smaller
'>' = Greater

BrickletThermocouple.get_temperature_callback_threshold¶

Function ID:	5
Request:	empty payload
Response:	option – Type: char, Range: See meanings, Default: 'x' min – Type: int32, Unit: 1/100 °C, Range: [-2³¹ to 2³¹ - 1], Default: 0 max – Type: int32, Unit: 1/100 °C, Range: [-2³¹ to 2³¹ - 1], Default: 0

Returns the threshold as set by set_temperature_callback_threshold.

The following meanings are defined for the elements of this function:

For option:

'x' = Off
'o' = Outside
'i' = Inside
'<' = Smaller
'>' = Greater

BrickletThermocouple.set_debounce_period¶

Function ID:	6
Request:	debounce – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 100
Response:	no response

Sets the period with which the threshold callback

CALLBACK_TEMPERATURE_REACHED

is triggered, if the threshold

set_temperature_callback_threshold

keeps being reached.

BrickletThermocouple.get_debounce_period¶

Function ID:	7
Request:	empty payload
Response:	debounce – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 100

Returns the debounce period as set by set_debounce_period.

Callbacks¶

BrickletThermocouple.CALLBACK_TEMPERATURE¶

Function ID:	8
Response:	temperature – Type: int32, Unit: 1/100 °C, Range: [-21000 to 180000]

This callback is triggered periodically with the period that is set by set_temperature_callback_period. The response value is the temperature of the thermocouple.

The CALLBACK_TEMPERATURE callback is only triggered if the temperature has changed since the last triggering.

BrickletThermocouple.CALLBACK_TEMPERATURE_REACHED¶

Function ID:	9
Response:	temperature – Type: int32, Unit: 1/100 °C, Range: [-21000 to 180000]

This callback is triggered when the threshold as set by set_temperature_callback_threshold is reached. The response value is the temperature of the thermocouple.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by set_debounce_period.

BrickletThermocouple.CALLBACK_ERROR_STATE¶

Function ID:	13
Response:	over_under – Type: bool open_circuit – Type: bool

This Callback is triggered every time the error state changes (see get_error_state).