New extrusion line, put in by a contractor in the spring. 1756-L83E with one 1756-EN2T, eleven remote racks hanging off it, eight 1734-AENTR and three 1756-EN2TR racks, plus twelve PowerFlex 755 drives on the same module.
Every morning when the operator hits line start and all the drives come up together, five or six of the racks fault 16#0204 connection timed out, and half the time the line stops on the interlocks. Once it's running it's fine all day.
We changed the cable to rack 7 because the crimp looked rough, and swapped the switch for a spare Stratix 5700, no luck there either. Link light on the EN2T blinks like mad through the start. Is it the switch, or is the EN2T on its way out? Is eleven racks and twelve 755s all coming up in the same second simply more than one EN2T can get through?
What firmware on the EN2T, and which Studio version? Before you swap anything else, open the EN2T's web page, Diagnostics, Ethernet Statistics if I remember right, and read the packets per second with the line running and again during a start.