EtherCAT: How are SM0 & SM1 sync managers typically used?

In EtherCAT, the sync managers SM0 and SM1 are typically used for CoE (CANOpen over EtherCAT) mailbox communication. Essentially, mailbox communication is used for non-cyclic data exchange between the EtherCAT master and the slave devices.

• SM0 is typically used as MbxOut (Mailbox Output), that is, for Slave->Master communication
• SM1 is typically used as MbxIn (Mailbox Input), that is, for Master->Slave communication

For details you should check your EtherCAT slave’s ESI file (EEPROM specification) or the ESI XML file which can often be downloaded from the manufacturer’s website.

Source and own analysis of a lot of ESI files.