Copper to fibre Media fibre converter not working with Ethercat

Hi guys.

This is really strange and would love any help.

We have a ABB AC500 PLC running (PM591 with CM579 Ethercat network to some ABB remote IO (CI511).
There are 2 media converter (Beckhoff CU1561) to convert from copper to fibre and back to copper. We can send data (i.e a digital output) but not receive signals. We bypassed the fibre with a Cat6 cable and all works normal.

We then replaced both media converters with new ones without any change then replaced the fibre that made no difference.

We tested the same setup 6 months ago with the same settings on both the CU1561 and all worked well.

For information, the CU1561 can be set up for Ethercat or IP, Ethercat you need the XML device file that it looks like is only available from Bechhoff's Twincat so we use IP (as 6 months before without problem.

We have really exhausted all avenues and would like any possible help.

Regards Matt

Have you tried Advantech converters? They have always worked well for me.

Maybe you have a broken fiber. Try another pair?

What is the status of the diagnostic LEDs when the fiber is connected? See page 20 of manual.