Python - Thermocouple Bricklet

This is the description of the Python API bindings for the Thermocouple Bricklet. General information and technical specifications for the Thermocouple Bricklet are summarized in its hardware description.

An installation guide for the Python API bindings is part of their general description.

Examples

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

Simple

Download (example_simple.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Thermocouple Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_thermocouple import BrickletThermocouple

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    t = BrickletThermocouple(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Get current temperature
    temperature = t.get_temperature()
    print("Temperature: " + str(temperature/100.0) + " °C")

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

Callback

Download (example_callback.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Thermocouple Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_thermocouple import BrickletThermocouple

# Callback function for temperature callback
def cb_temperature(temperature):
    print("Temperature: " + str(temperature/100.0) + " °C")

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    t = BrickletThermocouple(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Register temperature callback to function cb_temperature
    t.register_callback(t.CALLBACK_TEMPERATURE, cb_temperature)

    # Set period for temperature callback to 1s (1000ms)
    # Note: The temperature callback is only called every second
    #       if the temperature has changed since the last call!
    t.set_temperature_callback_period(1000)

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

Threshold

Download (example_threshold.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Thermocouple Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_thermocouple import BrickletThermocouple

# Callback function for temperature reached callback
def cb_temperature_reached(temperature):
    print("Temperature: " + str(temperature/100.0) + " °C")

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    t = BrickletThermocouple(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    t.set_debounce_period(10000)

    # Register temperature reached callback to function cb_temperature_reached
    t.register_callback(t.CALLBACK_TEMPERATURE_REACHED, cb_temperature_reached)

    # Configure threshold for temperature "greater than 30 °C"
    t.set_temperature_callback_threshold(">", 30*100, 0)

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

API

Generally, every method of the Python bindings can throw an tinkerforge.ip_connection.Error exception that has a value and a description property. value can have different values:

  • Error.TIMEOUT = -1
  • Error.NOT_ADDED = -6 (unused since Python bindings version 2.0.0)
  • Error.ALREADY_CONNECTED = -7
  • Error.NOT_CONNECTED = -8
  • Error.INVALID_PARAMETER = -9
  • Error.NOT_SUPPORTED = -10
  • Error.UNKNOWN_ERROR_CODE = -11
  • Error.STREAM_OUT_OF_SYNC = -12
  • Error.INVALID_UID = -13
  • Error.NON_ASCII_CHAR_IN_SECRET = -14

All methods listed below are thread-safe.

Basic Functions

BrickletThermocouple(uid, ipcon)
Parameters:
  • uid – Type: str
  • ipcon – Type: IPConnection
Returns:
  • thermocouple – Type: BrickletThermocouple

Creates an object with the unique device ID uid:

thermocouple = BrickletThermocouple("YOUR_DEVICE_UID", ipcon)

This object can then be used after the IP Connection is connected (see examples above).

BrickletThermocouple.get_temperature()
Returns:
  • temperature – Type: int, Range: [-231 to 231 - 1]

Returns the temperature of the thermocouple. The value is given in °C/100, e.g. a value of 4223 means that a temperature of 42.23 °C is measured.

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(averaging, thermocouple_type, filter)
Parameters:
  • averaging – Type: int, Range: See constants
  • thermocouple_type – Type: int, Range: See constants
  • filter – Type: int, Range: See constants
Returns:
  • None

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 default configuration is 16 samples, K type and 50Hz.

The following constants are available for this function:

For averaging:

  • BrickletThermocouple.AVERAGING_1 = 1
  • BrickletThermocouple.AVERAGING_2 = 2
  • BrickletThermocouple.AVERAGING_4 = 4
  • BrickletThermocouple.AVERAGING_8 = 8
  • BrickletThermocouple.AVERAGING_16 = 16

For thermocouple_type:

  • BrickletThermocouple.TYPE_B = 0
  • BrickletThermocouple.TYPE_E = 1
  • BrickletThermocouple.TYPE_J = 2
  • BrickletThermocouple.TYPE_K = 3
  • BrickletThermocouple.TYPE_N = 4
  • BrickletThermocouple.TYPE_R = 5
  • BrickletThermocouple.TYPE_S = 6
  • BrickletThermocouple.TYPE_T = 7
  • BrickletThermocouple.TYPE_G8 = 8
  • BrickletThermocouple.TYPE_G32 = 9

For filter:

  • BrickletThermocouple.FILTER_OPTION_50HZ = 0
  • BrickletThermocouple.FILTER_OPTION_60HZ = 1
BrickletThermocouple.get_configuration()
Return Object:
  • averaging – Type: int, Range: See constants
  • thermocouple_type – Type: int, Range: See constants
  • filter – Type: int, Range: See constants

Returns the configuration as set by set_configuration().

The following constants are available for this function:

For averaging:

  • BrickletThermocouple.AVERAGING_1 = 1
  • BrickletThermocouple.AVERAGING_2 = 2
  • BrickletThermocouple.AVERAGING_4 = 4
  • BrickletThermocouple.AVERAGING_8 = 8
  • BrickletThermocouple.AVERAGING_16 = 16

For thermocouple_type:

  • BrickletThermocouple.TYPE_B = 0
  • BrickletThermocouple.TYPE_E = 1
  • BrickletThermocouple.TYPE_J = 2
  • BrickletThermocouple.TYPE_K = 3
  • BrickletThermocouple.TYPE_N = 4
  • BrickletThermocouple.TYPE_R = 5
  • BrickletThermocouple.TYPE_S = 6
  • BrickletThermocouple.TYPE_T = 7
  • BrickletThermocouple.TYPE_G8 = 8
  • BrickletThermocouple.TYPE_G32 = 9

For filter:

  • BrickletThermocouple.FILTER_OPTION_50HZ = 0
  • BrickletThermocouple.FILTER_OPTION_60HZ = 1
BrickletThermocouple.get_error_state()
Return Object:
  • 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_api_version()
Returns:
  • api_version – Type: [int, ...], Length: 3, Range: [0 to 255]

Returns the version of the API definition (major, minor, revision) 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.

BrickletThermocouple.get_response_expected(function_id)
Parameters:
  • function_id – Type: int, Range: See constants
Returns:
  • response_expected – Type: bool

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 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 send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • BrickletThermocouple.FUNCTION_SET_TEMPERATURE_CALLBACK_PERIOD = 2
  • BrickletThermocouple.FUNCTION_SET_TEMPERATURE_CALLBACK_THRESHOLD = 4
  • BrickletThermocouple.FUNCTION_SET_DEBOUNCE_PERIOD = 6
  • BrickletThermocouple.FUNCTION_SET_CONFIGURATION = 10
BrickletThermocouple.set_response_expected(function_id, response_expected)
Parameters:
  • function_id – Type: int, Range: See constants
  • response_expected – Type: bool
Returns:
  • None

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 send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • BrickletThermocouple.FUNCTION_SET_TEMPERATURE_CALLBACK_PERIOD = 2
  • BrickletThermocouple.FUNCTION_SET_TEMPERATURE_CALLBACK_THRESHOLD = 4
  • BrickletThermocouple.FUNCTION_SET_DEBOUNCE_PERIOD = 6
  • BrickletThermocouple.FUNCTION_SET_CONFIGURATION = 10
BrickletThermocouple.set_response_expected_all(response_expected)
Parameters:
  • response_expected – Type: bool
Returns:
  • None

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

BrickletThermocouple.get_identity()
Return Object:
  • uid – Type: str, Length: up to 8
  • connected_uid – Type: str, Length: up to 8
  • position – Type: chr
  • hardware_version – Type: [int, ...], Length: 3, Range: [0 to 255]
  • firmware_version – Type: [int, ...], Length: 3, Range: [0 to 255]
  • device_identifier – Type: int, 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' or 'd'.

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

Callback Configuration Functions

BrickletThermocouple.register_callback(callback_id, function)
Parameters:
  • callback_id – Type: int
  • function – Type: callable
Returns:
  • None

Registers the given function with the given callback_id.

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

BrickletThermocouple.set_temperature_callback_period(period)
Parameters:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • None

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()
Returns:
  • period – Type: int, 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(option, min, max)
Parameters:
  • option – Type: chr, Range: See constants, Default: "x"
  • min – Type: int, Range: [-231 to 231 - 1]
  • max – Type: int, Range: [-231 to 231 - 1]
Returns:
  • None

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 default value is ('x', 0, 0).

The following constants are available for this function:

For option:

  • BrickletThermocouple.THRESHOLD_OPTION_OFF = "x"
  • BrickletThermocouple.THRESHOLD_OPTION_OUTSIDE = "o"
  • BrickletThermocouple.THRESHOLD_OPTION_INSIDE = "i"
  • BrickletThermocouple.THRESHOLD_OPTION_SMALLER = "<"
  • BrickletThermocouple.THRESHOLD_OPTION_GREATER = ">"
BrickletThermocouple.get_temperature_callback_threshold()
Return Object:
  • option – Type: chr, Range: See constants, Default: "x"
  • min – Type: int, Range: [-231 to 231 - 1]
  • max – Type: int, Range: [-231 to 231 - 1]

Returns the threshold as set by set_temperature_callback_threshold().

The following constants are available for this function:

For option:

  • BrickletThermocouple.THRESHOLD_OPTION_OFF = "x"
  • BrickletThermocouple.THRESHOLD_OPTION_OUTSIDE = "o"
  • BrickletThermocouple.THRESHOLD_OPTION_INSIDE = "i"
  • BrickletThermocouple.THRESHOLD_OPTION_SMALLER = "<"
  • BrickletThermocouple.THRESHOLD_OPTION_GREATER = ">"
BrickletThermocouple.set_debounce_period(debounce)
Parameters:
  • debounce – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100
Returns:
  • None

Sets the period with which the threshold callback

is triggered, if the threshold

keeps being reached.

BrickletThermocouple.get_debounce_period()
Returns:
  • debounce – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

Returns the debounce period as set by set_debounce_period().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the register_callback() function of the device object. The first parameter is the callback ID and the second parameter the callback function:

def my_callback(param):
    print(param)

thermocouple.register_callback(BrickletThermocouple.CALLBACK_EXAMPLE, my_callback)

The available constants with inherent number and type of parameters 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.

BrickletThermocouple.CALLBACK_TEMPERATURE
Callback Parameters:
  • temperature – Type: int, Range: [-231 to 231 - 1]

This callback is triggered periodically with the period that is set by set_temperature_callback_period(). The parameter 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
Callback Parameters:
  • temperature – Type: int, Range: [-231 to 231 - 1]

This callback is triggered when the threshold as set by set_temperature_callback_threshold() is reached. The parameter 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
Callback Parameters:
  • over_under – Type: bool
  • open_circuit – Type: bool

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

Constants

BrickletThermocouple.DEVICE_IDENTIFIER

This constant is used to identify a Thermocouple Bricklet.

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

BrickletThermocouple.DEVICE_DISPLAY_NAME

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