CU2508 - Real-time Ethernet port multiplier

ESL Protocol

The EtherCAT Switch Link protocol (ESL) from Beckhoff is a simple extension for the control of EtherCAT infrastructure components. It is currently used (as of 2010) for the operation of the ET2000 Industrial Ethernet Multichannel Probe and the CU2508.

The ESL data consist of 16 bytes of control data and information, which are added as a prefix (in front) or as a postfix (to the end) of an existing Ethernet data frame. The check sum (CRC) is adapted accordingly.

CU2508 ESL prefix

The ESL data are structured as follows:

ESL structure

Ethernet network monitors

The freely available network monitor Wireshark has contained an interpreter for the ESL protocol since the version 1.4.2.