Modbus - Current25 Bricklet

This is the description of the Modbus protocol for the Current25 Bricklet. General information and technical specifications for the Current25 Bricklet are summarized in its hardware description.

API

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

Basic Functions

BrickletCurrent25.get_current
Function ID:

1

Request:

empty payload

Response:
  • current -- int16

Returns the current of the sensor. The value is in mA and between -25000mA and 25000mA.

If you want to get the current periodically, it is recommended to use the CALLBACK_CURRENT callback and set the period with set_current_callback_period.

Advanced Functions

BrickletCurrent25.calibrate
Function ID:2
Request:empty payload
Response:no response

Calibrates the 0 value of the sensor. You have to call this function when there is no current present.

The zero point of the current sensor is depending on the exact properties of the analog-to-digital converter, the length of the Bricklet cable and the temperature. Thus, if you change the Brick or the environment in which the Bricklet is used, you might have to recalibrate.

The resulting calibration will be saved on the EEPROM of the Current Bricklet.

BrickletCurrent25.is_over_current
Function ID:

3

Request:

empty payload

Response:
  • over -- bool

Returns true if more than 25A were measured.

Note

To reset this value you have to power cycle the Bricklet.

BrickletCurrent25.get_analog_value
Function ID:

4

Request:

empty payload

Response:
  • value -- uint16

Returns the value as read by a 12-bit analog-to-digital converter. The value is between 0 and 4095.

Note

The value returned by get_current is averaged over several samples to yield less noise, while get_analog_value gives back raw unfiltered analog values. The only reason to use get_analog_value is, if you need the full resolution of the analog-to-digital converter.

If you want the analog value periodically, it is recommended to use the CALLBACK_ANALOG_VALUE callback and set the period with set_analog_value_callback_period.

BrickletCurrent25.get_identity
Function ID:

255

Request:

empty payload

Response:
  • uid -- char[8]
  • connected_uid -- char[8]
  • position -- char
  • hardware_version -- uint8[3]
  • firmware_version -- uint8[3]
  • device_identifier -- uint16

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

Callback Configuration Functions

BrickletCurrent25.set_current_callback_period
Function ID:

5

Request:
  • period -- uint32
Response:

no response

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

The CALLBACK_CURRENT callback is only triggered if the current has changed since the last triggering.

The default value is 0.

BrickletCurrent25.get_current_callback_period
Function ID:

6

Request:

empty payload

Response:
  • period -- uint32

Returns the period as set by set_current_callback_period.

BrickletCurrent25.set_analog_value_callback_period
Function ID:

7

Request:
  • period -- uint32
Response:

no response

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

The CALLBACK_ANALOG_VALUE callback is only triggered if the analog value has changed since the last triggering.

The default value is 0.

BrickletCurrent25.get_analog_value_callback_period
Function ID:

8

Request:

empty payload

Response:
  • period -- uint32

Returns the period as set by set_analog_value_callback_period.

BrickletCurrent25.set_current_callback_threshold
Function ID:

9

Request:
  • option -- char
  • min -- int16
  • max -- int16
Response:

no response

Sets the thresholds for the CALLBACK_CURRENT_REACHED callback.

The following options are possible:

Option Description
'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 meanings are defined for the parameters of this function:

  • x: off, for option
  • o: outside, for option
  • i: inside, for option
  • <: smaller, for option
  • >: greater, for option
BrickletCurrent25.get_current_callback_threshold
Function ID:

10

Request:

empty payload

Response:
  • option -- char
  • min -- int16
  • max -- int16

Returns the threshold as set by set_current_callback_threshold.

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

  • x: off, for option
  • o: outside, for option
  • i: inside, for option
  • <: smaller, for option
  • >: greater, for option
BrickletCurrent25.set_analog_value_callback_threshold
Function ID:

11

Request:
  • option -- char
  • min -- uint16
  • max -- uint16
Response:

no response

Sets the thresholds for the CALLBACK_ANALOG_VALUE_REACHED callback.

The following options are possible:

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

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

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

  • x: off, for option
  • o: outside, for option
  • i: inside, for option
  • <: smaller, for option
  • >: greater, for option
BrickletCurrent25.get_analog_value_callback_threshold
Function ID:

12

Request:

empty payload

Response:
  • option -- char
  • min -- uint16
  • max -- uint16

Returns the threshold as set by set_analog_value_callback_threshold.

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

  • x: off, for option
  • o: outside, for option
  • i: inside, for option
  • <: smaller, for option
  • >: greater, for option
BrickletCurrent25.set_debounce_period
Function ID:

13

Request:
  • debounce -- uint32
Response:

no response

Sets the period in ms with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

The default value is 100.

BrickletCurrent25.get_debounce_period
Function ID:

14

Request:

empty payload

Response:
  • debounce -- uint32

Returns the debounce period as set by set_debounce_period.

Callbacks

BrickletCurrent25.CALLBACK_CURRENT
Function ID:

15

Response:
  • current -- int16

This callback is triggered periodically with the period that is set by set_current_callback_period. The response value is the current of the sensor.

The CALLBACK_CURRENT callback is only triggered if the current has changed since the last triggering.

BrickletCurrent25.CALLBACK_ANALOG_VALUE
Function ID:

16

Response:
  • value -- uint16

This callback is triggered periodically with the period that is set by set_analog_value_callback_period. The response value is the analog value of the sensor.

The CALLBACK_ANALOG_VALUE callback is only triggered if the current has changed since the last triggering.

BrickletCurrent25.CALLBACK_CURRENT_REACHED
Function ID:

17

Response:
  • current -- int16

This callback is triggered when the threshold as set by set_current_callback_threshold is reached. The response value 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.

BrickletCurrent25.CALLBACK_ANALOG_VALUE_REACHED
Function ID:

18

Response:
  • value -- uint16

This callback is triggered when the threshold as set by set_analog_value_callback_threshold is reached. The response value is the analog value of the sensor.

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

BrickletCurrent25.CALLBACK_OVER_CURRENT
Function ID:19
Response:empty payload

This callback is triggered when an over current is measured (see is_over_current).