Modbus - Solid State Relay Bricklet

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

API

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

Basic Functions

BrickletSolidStateRelay.set_state
Function ID:

1

Request:
  • state -- bool
Response:

no response

Sets the state of the relays true means on and false means off.

Running monoflop timers will be overwritten if this function is called.

The default value is false.

BrickletSolidStateRelay.get_state
Function ID:

2

Request:

empty payload

Response:
  • state -- bool

Returns the state of the relay, true means on and false means off.

Advanced Functions

BrickletSolidStateRelay.set_monoflop
Function ID:

3

Request:
  • state -- bool
  • time -- uint32
Response:

no response

The first parameter is the desired state of the relay (true means on and false means off). The second parameter indicates the time (in ms) that the relay should hold the state.

If this function is called with the parameters (true, 1500): The relay will turn on and in 1.5s it will turn off again.

A monoflop can be used as a failsafe mechanism. For example: Lets assume you have a RS485 bus and a Solid State Relay Bricklet connected to one of the slave stacks. You can now call this function every second, with a time parameter of two seconds. The relay will be on all the time. If now the RS485 connection is lost, the relay will turn off in at most two seconds.

BrickletSolidStateRelay.get_monoflop
Function ID:

4

Request:

empty payload

Response:
  • state -- bool
  • time -- uint32
  • time_remaining -- uint32

Returns the current state and the time as set by set_monoflop as well as the remaining time until the state flips.

If the timer is not running currently, the remaining time will be returned as 0.

BrickletSolidStateRelay.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

Callbacks

BrickletSolidStateRelay.CALLBACK_MONOFLOP_DONE
Function ID:

5

Response:
  • state -- bool

This callback is triggered whenever the monoflop timer reaches 0. The parameter is the current state of the relay (the state after the monoflop).