Having communications issues using a SCADA system running TCP/IP and then using a Modbus Ethernet Serial Server to connect to two Modbus slaves. Any help or hints?

Have tried altering the serial delay and this helps a bit. Anyone else had this issue previously?

Thanks!

 

This is probably going to be hardware dependent on the TCP-serial bridge you're using (probably doesn't have anything to do with the protocols, which is all the information you've shared), so you'll get a lot more helpful answers if you describe the hardware setup.

That having been said, I had what might be a similar problem using a Prosoft bridge device trying to talk to a few (less than 5) ABB ACS-550 drives on RS485. The problem turned out to be that the ABB's received the request, viewed it as valid, and responded. Problem is they insisted on responding in like 20ms or something like that, and the Prosoft didn't release control of the bus (it was jumpered to be two-wire, which is what the ABB's need) for like 50ms after it was done talking. The ABB's couldn't overcome the influence of the bridge on the line voltage so the response looked mangled to the bridge and it ignored the response, and the ABB's didn't have a parameter to control response delay, to keep them from responding till after the bridge released the bus.