mettler toledo ACT350 and CompactLogix

I have 5 ACT350 scale controllers networked to a CompactLogix L33ER processor running V28. One or more scale controllers very rarely will drop communications. The only thing that will get it going is to cycle power to the aCT350.

All 5 scale controllers are connected to a Moxa EDS-516A Managed, 16 port switch. They share the switch with 3 Weintek HMI's. This switch is connected to another Moxa EDS-516A switch. This 2nd switch has 12 Powerflex 525 VFD's connected to it, plus the CompactLogix processor.

The VFD's and HMI's communicate fine, never a fault.

Any idea why the ACT350's would drop comm?

Any recommended settings in the Moxa managed switches that might improve the situation?

One thing I intend to try since this CompactLogix has 2 ethernet ports is to connect one port of the CompactLogix to one switch and the other port to the other switch and remove the connection between the switches. Perhaps the jumping between switches is causing an issue?

TIA...

The 1769-L33ER has only one ethernet port though it has two rj45 connectors, the two connectors are used to impelment DLR. Th new compaclogix 5380 and 5480 they do have 2 and 3 ethernet ports respectively.

My first inclination would be to look at the RPI settings on each device. If the drives, for instance, are running fans, blowers, conveyors etc., they can usually be set slower than the default RPI when they are added. I've read on here that its good practice to offset the RPI's so they aren't trying to talk all at once.