Python - Energy Monitor Bricklet

This is the description of the Python API bindings for the Energy Monitor Bricklet. General information and technical specifications for the Energy Monitor 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 Energy Monitor Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_energy_monitor import BrickletEnergyMonitor

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

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

    # Get current Energy Data
    voltage, current, energy, real_power, apparent_power, reactive_power, power_factor, \
      frequency = em.get_energy_data()

    print("Voltage: " + str(voltage/100.0) + " V")
    print("Current: " + str(current/100.0) + " A")
    print("Energy: " + str(energy/100.0) + " Wh")
    print("Real Power: " + str(real_power/100.0) + " h")
    print("Apparent Power: " + str(apparent_power/100.0) + " VA")
    print("Reactive Power: " + str(reactive_power/100.0) + " VAR")
    print("Power Factor: " + str(power_factor/1000.0))
    print("Frequency: " + str(frequency/100.0) + " Hz")

    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 Energy Monitor Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_energy_monitor import BrickletEnergyMonitor

# Callback function for Energy Data callback
def cb_energy_data(voltage, current, energy, real_power, apparent_power, reactive_power,
                   power_factor, frequency):
    print("Voltage: " + str(voltage/100.0) + " V")
    print("Current: " + str(current/100.0) + " A")
    print("Energy: " + str(energy/100.0) + " Wh")
    print("Real Power: " + str(real_power/100.0) + " h")
    print("Apparent Power: " + str(apparent_power/100.0) + " VA")
    print("Reactive Power: " + str(reactive_power/100.0) + " VAR")
    print("Power Factor: " + str(power_factor/1000.0))
    print("Frequency: " + str(frequency/100.0) + " Hz")
    print("")

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

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

    # Register Energy Data callback to function cb_energy_data
    em.register_callback(em.CALLBACK_ENERGY_DATA, cb_energy_data)

    # Set period for Energy Data callback to 1s (1000ms)
    em.set_energy_data_callback_configuration(1000, False)

    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

BrickletEnergyMonitor(uid, ipcon)
Parameters:
  • uid -- string
  • ipcon -- IPConnection

Creates an object with the unique device ID uid:

energy_monitor = BrickletEnergyMonitor("YOUR_DEVICE_UID", ipcon)

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

BrickletEnergyMonitor.get_energy_data()
Return type:(int, int, int, int, int, int, int, int)

Returns all of the measurements that are done by the Energy Monitor Bricklet.

  • Voltage (V): Voltage RMS with a resolution of 10mV (example: 230.05V = 23005)
  • Current (A): Current RMS with a resolution of 10mA (example: 1.42A = 142)
  • Energy (Wh): Energy (integrated over time) with a resolution of 10mWh (example: 1.1kWh = 110000)
  • Real Power (W): Real Power with a resolution of 10mW (example: 1234.56W = 123456)
  • Apparent Power (VA): Apparent Power with a resolution of 10mVA (example: 1234.56VA = 123456)
  • Reactive Power (VAR): Reactive Power with a resolution of 10mVAR (example: 1234.56VAR = 123456)
  • Power Factor: Power Factor with a resolution of 1/1000 (example: PF 0.995 = 995)
  • Frequency (Hz): AC Frequency of the mains voltage with a resolution of 1/100 Hz (example: 50Hz = 5000)

The frequency is recalculated every 6 seconds.

All other values are integrated over 10 zero-crossings of the voltage sine wave. With a standard AC mains voltage frequency of 50Hz this results in a 5 measurements per second (or an integration time of 200ms per measurement).

If no voltage transformer is connected, the Bricklet will use the current waveform to calculate the frequency and it will use an integration time of 10 zero-crossings of the current waveform.

The returned namedtuple has the variables voltage, current, energy, real_power, apparent_power, reactive_power, power_factor and frequency.

BrickletEnergyMonitor.reset_energy()
Return type:None

Sets the energy value (see get_energy_data()) back to 0Wh.

BrickletEnergyMonitor.get_waveform()
Return type:[int, int, ..1533x.., int]

Returns a snapshot of the voltage and current waveform. The values in the returned array alternate between voltage and current. The data from one getter call contains 768 data points for voltage and current, which correspond to about 3 full sine waves.

The voltage is given with a resolution of 100mV and the current is given with a resolution of 10mA.

This data is meant to be used for a non-realtime graphical representation of the voltage and current waveforms.

BrickletEnergyMonitor.get_transformer_status()
Return type:(bool, bool)

Returns true if a voltage/current transformer is connected to the Bricklet.

The returned namedtuple has the variables voltage_transformer_connected and current_transformer_connected.

BrickletEnergyMonitor.set_transformer_calibration(voltage_ratio, current_ratio, phase_shift)
Parameters:
  • voltage_ratio -- int
  • current_ratio -- int
  • phase_shift -- int
Return type:

None

Sets the transformer ratio for the voltage and current transformer in 1/100 form.

Example: If your mains voltage is 230V, you use 9V voltage transformer and a 1V:30A current clamp your voltage ratio is 230/9 = 25.56 and your current ratio is 30/1 = 30.

In this case you have to set the values 2556 and 3000 for voltage ratio and current ratio.

The calibration is saved in non-volatile memory, you only have to set it once.

By default the voltage ratio is set to 1923 and the current ratio is set to 3000.

Set the phase shift to 0. It is for future use and currently not supported by the Bricklet.

BrickletEnergyMonitor.get_transformer_calibration()
Return type:(int, int, int)

Returns the transformer calibration as set by set_transformer_calibration().

The returned namedtuple has the variables voltage_ratio, current_ratio and phase_shift.

BrickletEnergyMonitor.calibrate_offset()
Return type:None

Calling this function will start an offset calibration. The offset calibration will integrate the voltage and current waveform over a longer time period to find the 0 transition point in the sine wave.

The Bricklet comes with a factory-calibrated offset value, you should not have to call this function.

If you want to re-calibrate the offset we recommend that you connect a load that has a smooth sinusoidal voltage and current waveform. Alternatively you can also short both inputs.

The calibration is saved in non-volatile memory, you only have to set it once.

Advanced Functions

BrickletEnergyMonitor.get_api_version()
Return type:[int, int, int]

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.

BrickletEnergyMonitor.get_response_expected(function_id)
Parameters:function_id -- int
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.

The following constants are available for this function:

  • BrickletEnergyMonitor.FUNCTION_RESET_ENERGY = 2
  • BrickletEnergyMonitor.FUNCTION_SET_TRANSFORMER_CALIBRATION = 5
  • BrickletEnergyMonitor.FUNCTION_CALIBRATE_OFFSET = 7
  • BrickletEnergyMonitor.FUNCTION_SET_ENERGY_DATA_CALLBACK_CONFIGURATION = 8
  • BrickletEnergyMonitor.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletEnergyMonitor.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletEnergyMonitor.FUNCTION_RESET = 243
  • BrickletEnergyMonitor.FUNCTION_WRITE_UID = 248
BrickletEnergyMonitor.set_response_expected(function_id, response_expected)
Parameters:
  • function_id -- int
  • response_expected -- bool
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.

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:

  • BrickletEnergyMonitor.FUNCTION_RESET_ENERGY = 2
  • BrickletEnergyMonitor.FUNCTION_SET_TRANSFORMER_CALIBRATION = 5
  • BrickletEnergyMonitor.FUNCTION_CALIBRATE_OFFSET = 7
  • BrickletEnergyMonitor.FUNCTION_SET_ENERGY_DATA_CALLBACK_CONFIGURATION = 8
  • BrickletEnergyMonitor.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletEnergyMonitor.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletEnergyMonitor.FUNCTION_RESET = 243
  • BrickletEnergyMonitor.FUNCTION_WRITE_UID = 248
BrickletEnergyMonitor.set_response_expected_all(response_expected)
Parameters:response_expected -- bool
Return type:None

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

BrickletEnergyMonitor.get_spitfp_error_count()
Return type:(int, int, int, 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.

The returned namedtuple has the variables error_count_ack_checksum, error_count_message_checksum, error_count_frame and error_count_overflow.

BrickletEnergyMonitor.set_bootloader_mode(mode)
Parameters:mode -- int
Return 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:

  • BrickletEnergyMonitor.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletEnergyMonitor.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletEnergyMonitor.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletEnergyMonitor.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletEnergyMonitor.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BrickletEnergyMonitor.BOOTLOADER_STATUS_OK = 0
  • BrickletEnergyMonitor.BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletEnergyMonitor.BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletEnergyMonitor.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletEnergyMonitor.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletEnergyMonitor.BOOTLOADER_STATUS_CRC_MISMATCH = 5
BrickletEnergyMonitor.get_bootloader_mode()
Return type:int

Returns the current bootloader mode, see set_bootloader_mode().

The following constants are available for this function:

  • BrickletEnergyMonitor.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletEnergyMonitor.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletEnergyMonitor.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletEnergyMonitor.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletEnergyMonitor.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
BrickletEnergyMonitor.set_write_firmware_pointer(pointer)
Parameters:pointer -- int
Return type:None

Sets the firmware pointer for 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.

BrickletEnergyMonitor.write_firmware(data)
Parameters:data -- [int, int, ..61x.., int]
Return type:int

Writes 64 Bytes of firmware at the position as written by 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.

BrickletEnergyMonitor.set_status_led_config(config)
Parameters:config -- int
Return type:None

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:

  • BrickletEnergyMonitor.STATUS_LED_CONFIG_OFF = 0
  • BrickletEnergyMonitor.STATUS_LED_CONFIG_ON = 1
  • BrickletEnergyMonitor.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletEnergyMonitor.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletEnergyMonitor.get_status_led_config()
Return type:int

Returns the configuration as set by set_status_led_config()

The following constants are available for this function:

  • BrickletEnergyMonitor.STATUS_LED_CONFIG_OFF = 0
  • BrickletEnergyMonitor.STATUS_LED_CONFIG_ON = 1
  • BrickletEnergyMonitor.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletEnergyMonitor.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletEnergyMonitor.get_chip_temperature()
Return type:int

Returns the temperature in °C 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.

BrickletEnergyMonitor.reset()
Return type:None

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!

BrickletEnergyMonitor.write_uid(uid)
Parameters:uid -- int
Return type:None

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.

BrickletEnergyMonitor.read_uid()
Return type:int

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

BrickletEnergyMonitor.get_identity()
Return type:(str, str, chr, [int, int, int], [int, int, int], 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' 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.

Callback Configuration Functions

BrickletEnergyMonitor.register_callback(callback_id, function)
Parameters:
  • callback_id -- int
  • function -- callable
Return type:

None

Registers the given function with the given callback_id.

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

BrickletEnergyMonitor.set_energy_data_callback_configuration(period, value_has_to_change)
Parameters:
  • period -- int
  • value_has_to_change -- bool
Return type:

None

The period in ms is the period with which the CALLBACK_ENERGY_DATA callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

The default value is (0, false).

BrickletEnergyMonitor.get_energy_data_callback_configuration()
Return type:(int, bool)

Returns the callback configuration as set by set_energy_data_callback_configuration().

The returned namedtuple has the variables period and value_has_to_change.

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)

energy_monitor.register_callback(BrickletEnergyMonitor.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.

BrickletEnergyMonitor.CALLBACK_ENERGY_DATA
Parameters:
  • voltage -- int
  • current -- int
  • energy -- int
  • real_power -- int
  • apparent_power -- int
  • reactive_power -- int
  • power_factor -- int
  • frequency -- int

This callback is triggered periodically according to the configuration set by set_energy_data_callback_configuration().

The parameters are the same as get_energy_data().

Constants

BrickletEnergyMonitor.DEVICE_IDENTIFIER

This constant is used to identify a Energy Monitor 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.

BrickletEnergyMonitor.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Energy Monitor Bricklet.