Comm Modbus

  • Thread starter Mario R Domenici
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Thread Starter

Mario R Domenici

I've modbus config with PLC GE-9030 4-wire cabling
8 slaves (weight belt n weighfeeders system).
When I connect only 1 slave, system works and the parameter are read normally, but if I connect a second slave the master's comm is interrupted.

How can I solve this problem ?

Tks in advanced.

Mário R Domenici


Check the Modbus slave address on the weigh feeders. If multiple slaves have the same address then the master will see comm errors. Hope this helps.
You don't state what module you're using as the RTU master in the PLC. If you're using Horner's RTU Master (HE693RTM705), then check the first word in the Slave Control Block (SCB). If it's not 1 or 0, the module has detected an error and stopped communicating with the slave. Your RTM705 manual has list of error codes. If you don't have a manual, download one from Horner's website (

Best regards,

Drake Fink
Application Engineer
GE Fanuc Automation