RPS Telegram

Owned by Matthias Kassner
11-Jul-2024
2 min read

Switch Telegrams originating from PTM 21x pushbutton transmitter modules or PTM 535 button transmitters are expanded to RPS telegram format by the first receiver (which can be either an ERP1 Repeater or an ERP1 Receiver). RPS telegram format is then used to represent the switch status in EnOcean systems.

R-ORG

RPS telegrams use R-ORG 0xF6

Telegram Payload

RPS telegrams contain one byte of data payload which can identify the action of up to two buttons. In addition, Bit 4 of the STATUS field within the ERP1 telegram identifies the following special cases:

  • No button is pressed (only the energy bar of the PTM 21x module or only the ECO 260 harvester connected to the PTM 535 module is actuated)

  • More than two buttons are pressed at the same time

If one of these special cases applies, then Bit 4 of the STATUS field within the ERP1 telegram is set to 0 (this case is sometimes called an UxS telegram). Otherwise, Bit 4 of the STATUS field within the ERP1 telegram is set to 1 (this case is sometimes called TxS telegram).

The format of the RPS telegram payload is shown below.

image-20240705-080055.png
RPS Telegram Payload

The RPS telegram payload contains the following fields:

  • FIRST ACTION and SECOND ACTION
    These FIRST ACTION and SECOND ACTION fields encode the button that was pressed; each field can encode one button action. For legacy reasons, these fields are 3 bit wide as the first EnOcean PTM modules had 8 buttons. The action button encoding is as follows:

    • 0b000: Button AI is actuated

    • 0b001: Button A0 is actuated

    • 0b010: Button BI is actuated

    • 0b011: Button B0 is actuated

    • Others: Not used

  • DIRECTION
    The DIRECTION field encodes the direction of the actuation. Note that the direction of actuation is always the same even if more than one button is pressed. It is mechanically not possible to have a release action for one button at the same time as a press action for another button on the same module.
    The encoding of the actuation direction is as follows:

    • 0b0: Release direction

    • 0b1: Press direction

  • DUAL ACTION
    The DUAL ACTION field specifies if a second button action (as specified by the SECOND ACTION field) occurred and the content of the SECOND ACTION field is therefore valid. This is required as the SECOND ACTION field cannot encode the case of “No Action”.