ERP1 Switch Telegram Format

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

ERP1 defines a special (shortened) format for telegrams transmitted by kinetic-harvesting switches such as PTM 21x or PTM 535 + ECO 260. This format reduces the telegram size from 8 byte for the standard ERP1 Broadcast Data Telegram format to 6 byte for the ERP1 Switch Telegram format.

The size reduction is achieved by the following measures.

  • RORG
    The RORG field is shortened from 8 bit to 4 bit which are called CHOICE

  • STATUS
    The STATUS field is not present

  • HASH
    The HASH field is shortened from 8 bit to 4 bit

The ERP1 Switch Telegram format is shown below. The DATA payload of this telegram is described here.

image-20240705-113655.png
ERP1 Switch Telegram Format

CHOICE Field

The CHOICE field encodes the combination of supported RORG and STATUS values. The following settings are possible for the CHOICE field:

  • 0b0101 (5)
    The setting of 0b0101 encodes the following parameters:

    • RORG = 0xF6
      Rocker Pushbutton Module

    • STATUS = 0x20
      No button pressed or more than two buttons pressed (UxD)

  • 0b0110 (6)
    The setting of 0b0110 encodes the following parameters:

    • RORG = 0xF6
      Rocker Pushbutton Module

    • STATUS = 0x30
      One or two buttons pressed (TxD)

Note that the CHOICE field takes the role of the R-ORG field in ERP1 telegrams. For compatibility reasons, there are therefore no R-ORG values starting with 0b0101 or 0b0110.

ERP1 Switch Telegram Processing

To ensure system-level compatibility, the ERP1 Switch Telegrams are expanded into standard ERP1 Broadcast Data Telegrams (with the RORG and STATUS translation described above) at EnOcean ERP1 radio gateways (such as TCM 310 or TCM 515) or EnOcean ERP1 repeaters.