Most field issues are not EtherCAT protocol faults but physical/system integration problems:
ecmcMain.ui and inspect overall status:ethercat slaves) and/or iocsh.OP.caqtdm -macro "IOC=<iocname>" ecmcMain.ui
red channels are not automatically wrong; they can also indicate intentionally unconnected signals.
Do not blindly restart the IOC with partially working EtherCAT hardware. This can leave the IOC in a non-recovering startup state.
Use the pages below for terminal/drive-specific diagnostics: