This is the description of the Python API bindings for the Industrial Dual 0-20mA Bricklet. General information and technical specifications for the Industrial Dual 0-20mA Bricklet are summarized in its hardware description.
An installation guide for the Python API bindings is part of their general description.
The example code below is Public Domain (CC0 1.0).
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change to your UID
from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_industrial_dual_0_20ma import IndustrialDual020mA
if __name__ == "__main__":
ipcon = IPConnection() # Create IP connection
dual020 = IndustrialDual020mA(UID, ipcon) # Create device object
ipcon.connect(HOST, PORT) # Connect to brickd
# Don't use device before ipcon is connected
# Get current current for sensor 1 (unit is nA)
current = dual020.get_current(1)
print('Current: ' + str(current/(1000.0*1000.0)) + ' mA')
raw_input('Press key to exit\n') # Use input() in Python 3
ipcon.disconnect()
|
Download (example_callback.py)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change to your UID
from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_industrial_dual_0_20ma import IndustrialDual020mA
# Callback function for current callback (parameter has unit nA)
def cb_current(sensor, current):
print('Current (sensor ' + str(sensor) + '): ' + str(current/(1000.0*1000.0)) + ' mA')
if __name__ == "__main__":
ipcon = IPConnection() # Create IP connection
dual020 = IndustrialDual020mA(UID, ipcon) # Create device object
ipcon.connect(HOST, PORT) # Connect to brickd
# Don't use device before ipcon is connected
# Set Period (sensor 1) for current callback to 1s (1000ms)
# Note: The callback is only called every second if the
# current has changed since the last call!
dual020.set_current_callback_period(1, 1000)
# Register current callback to function cb_current
dual020.register_callback(dual020.CALLBACK_CURRENT, cb_current)
raw_input('Press key to exit\n') # Use input() in Python 3
ipcon.disconnect()
|
Download (example_threshold.py)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change to your UID
from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_industrial_dual_0_20ma import IndustrialDual020mA
# Callback for current greater than 10mA
def cb_reached(sensor, current):
print('Current (sensor' + str(sensor) + ') is greater than 10mA: ' + str(current/(1000.0*1000.0)))
if __name__ == "__main__":
ipcon = IPConnection() # Create IP connection
dual020 = IndustrialDual020mA(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)
dual020.set_debounce_period(10000)
# Register threshold reached callback to function cb_reached
dual020.register_callback(dual020.CALLBACK_CURRENT_REACHED, cb_reached)
# Configure threshold (sensor 1) for "greater than 10mA" (unit is nA)
dual020.set_current_callback_threshold(1, '>', 10*1000*1000, 0)
raw_input('Press key to exit\n') # Use input() in Python 3
ipcon.disconnect()
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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:
All methods listed below are thread-safe.
Two sensors can be connected to the Bricklet. Functions that are related directly to a sensor have a sensor parameter to specify one of the two sensors. Valid values for the sensor parameter are 0 and 1.
Parameters: |
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Creates an object with the unique device ID uid:
industrial_dual_0_20ma = IndustrialDual020mA("YOUR_DEVICE_UID", ipcon)
This object can then be used after the IP Connection is connected (see examples above).
Parameters: | sensor -- int |
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Return type: | int |
Returns the current of the specified sensor (0 or 1). The value is in nA and between 0nA and 22505322nA (22.5mA).
It is possible to detect if an IEC 60381-1 compatible sensor is connected and if it works probably.
If the returned current is below 4mA, there is likely no sensor connected or the sensor may be defect. If the returned current is over 20mA, there might be a short circuit or the sensor may be defect.
If you want to get the current periodically, it is recommended to use the callback CALLBACK_CURRENT and set the period with set_current_callback_period().
Parameters: | rate -- int |
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Return type: | None |
Sets the sample rate to either 240, 60, 15 or 4 samples per second. The resolution for the rates is 12, 14, 16 and 18 bit respectively.
Value | Description |
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0 | 240 samples per second, 12 bit resolution |
1 | 60 samples per second, 14 bit resolution |
2 | 15 samples per second, 16 bit resolution |
3 | 4 samples per second, 18 bit resolution |
The default value is 3: 4 samples per second with 18 bit resolution.
The following constants are available for this function:
Return type: | int |
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Returns the sample rate as set by set_sample_rate().
The following constants are available for this function:
Return type: | [int, int, int] |
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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.
Parameters: | function_id -- int |
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Return 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.
See set_response_expected() for the list of function ID constants available for this function.
Parameters: |
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Return type: | 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 and callbacks it is always disabled.
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 function ID constants are available for this function:
Parameters: | response_expected -- bool |
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Return type: | None |
Changes the response expected flag for all setter and callback configuration functions of this device at once.
Return type: | (str, str, chr, [int, int, int], [int, int, int], int) |
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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.
The returned namedtuple has the variables uid, connected_uid, position, hardware_version, firmware_version and device_identifier.
Parameters: |
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Return type: | None |
Registers a callback with ID id to the function callback. The available IDs with corresponding function signatures are listed below.
Parameters: |
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Return type: | None |
Sets the period in ms with which the CALLBACK_CURRENT callback is triggered periodically for the given sensor. A value of 0 turns the callback off.
CALLBACK_CURRENT is only triggered if the current has changed since the last triggering.
The default value is 0.
Parameters: | sensor -- int |
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Return type: | int |
Returns the period as set by set_current_callback_period().
Parameters: |
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Return type: | None |
Sets the thresholds for the CALLBACK_CURRENT_REACHED callback for the given sensor.
The following options are possible:
Option | Description |
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'x' | Callback is turned off |
'o' | Callback is triggered when the current is outside the min and max values |
'i' | Callback is triggered when the current is inside the min and max values |
'<' | Callback is triggered when the current is smaller than the min value (max is ignored) |
'>' | Callback is triggered when the current is greater than the min value (max is ignored) |
The default value is ('x', 0, 0).
The following constants are available for this function:
Parameters: | sensor -- int |
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Return type: | (chr, int, int) |
Returns the threshold as set by set_current_callback_threshold().
The following constants are available for this function:
The returned namedtuple has the variables option, min and max.
Parameters: | debounce -- int |
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Return type: | None |
Sets the period in ms with which the threshold callback
is triggered, if the threshold
keeps being reached.
The default value is 100.
Return type: | int |
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Returns the debounce period as set by set_debounce_period().
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)
industrial_dual_0_20ma.register_callback(IndustrialDual020mA.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.
Parameters: |
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This callback is triggered periodically with the period that is set by set_current_callback_period(). The parameter is the current of the sensor.
CALLBACK_CURRENT is only triggered if the current has changed since the last triggering.
Parameters: |
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This callback is triggered when the threshold as set by set_current_callback_threshold() is reached. The parameter is the current of the sensor.
If the threshold keeps being reached, the callback is triggered periodically with the period as set by set_debounce_period().
This constant is used to identify a Industrial Dual 0-20mA Bricklet.
The get_identity() function and the CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.