Hi,
I am trying to set modbus RS485 2 wire communications with a Newport INF-B process meter. My end goal is to use a PLC to communicate with this device, but I have have trouble getting that going. So to verify I have meter settings and wiring correct I am using my PC to start with. I have a MOXA Uport usb serial device connected to my computer. The MOXA is setup for RS485 two wire on port one (Com 1).
I started with the software that came with the meter, Infinity Configuration software, and used the modbus section of the software to send a read request to register HEX 0B (Dec 11). I am also using Serial Port Monitor software to see the commands being sent and received through the serial port. Attached are screen captures of the Infinity and Serial Port Monitor. There were no problems using the Infinity software.
Then I tried using Modbus Poll software to read the same register. Attached is a screen shot of the Modbus Poll Settings and the Serial Port Monitor after the command was sent. You can see that only 2 of the four bytes were returned and there is a checksum error. This is the same problem I am having when trying to use the PLC.
The command sent from each of these applications looks the same. Why the difference in response?
I am hoping someone can help me correct this issue?
I am trying to set modbus RS485 2 wire communications with a Newport INF-B process meter. My end goal is to use a PLC to communicate with this device, but I have have trouble getting that going. So to verify I have meter settings and wiring correct I am using my PC to start with. I have a MOXA Uport usb serial device connected to my computer. The MOXA is setup for RS485 two wire on port one (Com 1).
I started with the software that came with the meter, Infinity Configuration software, and used the modbus section of the software to send a read request to register HEX 0B (Dec 11). I am also using Serial Port Monitor software to see the commands being sent and received through the serial port. Attached are screen captures of the Infinity and Serial Port Monitor. There were no problems using the Infinity software.
Then I tried using Modbus Poll software to read the same register. Attached is a screen shot of the Modbus Poll Settings and the Serial Port Monitor after the command was sent. You can see that only 2 of the four bytes were returned and there is a checksum error. This is the same problem I am having when trying to use the PLC.
The command sent from each of these applications looks the same. Why the difference in response?
I am hoping someone can help me correct this issue?
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