Palletiser cell, Beckhoff CX5140 on TwinCAT 3.1 build 4024, an EtherCAT line of 22 slaves. EK1100 couplers, four EL7211 servo terminals, an EL6751 CANopen master on the end. PLC task 1 ms, EtherCAT task the same.

Since last week, a few times a shift, slaves 14 to 22 flip to SAFEOP and the axes on 15 to 18 trip out with a following error. WcState on those slaves goes to 1 while it's happening and the master's Lost Frames counter climbs by a few hundred each time. Slaves 1 to 13 sit there in OP through all of it.

I've tried the task cycle at 2 ms, no change, and I reloaded the config, same again. I guess it could be the master overloaded, but CPU on the Real-Time tab is only 30 percent. Any thoughts?