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I am attempting to establish Modbus communications between a Banner DX80 Sure Cross Performance Gateway and a Rockwell Micro 820 PLC using the PLC's built-in RS-485 port.
I have been working with both Banner & Rockwell tech support and have come to an impasse.
I have the PLC as Master and the DX80 as Slave (the Banner cannot be a Modbus Master).
When I trigger a Modbus Read from the PLC, the #2 light on the DX 80 flashes Red indicating it received some traffic, but was unable to understand it. The Modbus command on the PLC gives and error code of 55 which Rockwell tells me is a timeout due to no response from the slave.
I have checked all comm parameters on both devices and everything seems correct.
Rockwell tells me that I don't need termination or biasing resistors on the RS-485 lines.
Anyone with any experience with this particular configuration or with Modbus Communications on the Micro 800 series have any suggestions?
I have been working with both Banner & Rockwell tech support and have come to an impasse.
I have the PLC as Master and the DX80 as Slave (the Banner cannot be a Modbus Master).
When I trigger a Modbus Read from the PLC, the #2 light on the DX 80 flashes Red indicating it received some traffic, but was unable to understand it. The Modbus command on the PLC gives and error code of 55 which Rockwell tells me is a timeout due to no response from the slave.
I have checked all comm parameters on both devices and everything seems correct.
Rockwell tells me that I don't need termination or biasing resistors on the RS-485 lines.
Anyone with any experience with this particular configuration or with Modbus Communications on the Micro 800 series have any suggestions?