Hello! I am currently troubleshooting some issues with ASCII serial communications over RS485 using COMMREQ functions. I have included a diagram of our wiring setup for the COM2 (SUBD15) port - can you confirm if it is accurate? When connecting an RS485 USB converter to the port to monitor outgoing PLC commands, we are noticing that the bytes are not being displayed correctly. Any helpful tips or overlooked settings related to COMMREQ that could resolve this issue would be highly valued. Thank you!
Everything is fine, with B being equal to minus and A being equal to plus.
Hi there! I noticed your dilemma with ASCII serial communications over RS485. I've dealt with a similar situation before. You are right in checking your wiring setup, as that could often be the root of the problem. However, the diagram wasn't included in the post, so please do make sure to update it, so we can assess it properly. Also, issues of incorrectly displayed bytes could potentially be due to baud rate mismatches or incorrect parity bits setting. You might want to double-check your COM settings for parity, baud rate, stop bits and data bits and ensure that both devices are configured identically. Moreover, check your COMMREQ syntax and settings in PLC as it is critical for successful communication.
Hey there! It sounds like you're facing quite a challenge with your RS485 setup. First, I’d recommend double-checking that your wiring matches the RS485 standard; make sure the A and B lines are correctly connected. Sometimes, the issue can stem from mismatched baud rates or incorrect parity settings in your COMMREQ functions - these can easily lead to garbled data. Also, ensure that your USB converter's settings align with the PLC's configuration. Have you tried monitoring the COM2 port using a different tool or terminal software? It might help you isolate whether the issue is with the COMMREQ functions or potentially with the converter itself. Good luck!
Hey there! It sounds like you're facing a frustrating issue with your RS485 setup. One thing to double-check is whether the baud rate and settings (like parity and stop bits) on both the PLC and the USB converter match; mismatches can cause garbled communication. Also, ensure that your wiring is configured properly for a differential signal, as RS485 relies on that for accurate transmission. Additionally, if you’re using COMMREQ, make sure that any necessary buffers are set up correctly and that you’re interpreting the data format properly on the receiving end. Sometimes, the problem can stem from minor software configuration settings, so it might be worth running through those again too. Good luck, and hope you get it sorted out!
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Answer: 1. How can I troubleshoot ASCII serial communications over RS485 using COMMREQ functions for Emerson/GE RX3i PLC? - To troubleshoot ASCII serial communications over RS485 using COMMREQ functions, you can start by confirming the accuracy of your wiring setup and checking for any overlooked settings related to COMMREQ.
Answer: - If the bytes are not being displayed correctly when monitoring outgoing PLC commands with an RS485 USB converter, you may need to double-check your wiring setup, ensure the correct baud rate and parity settings are configured, and review the COMMREQ function parameters for any potential errors.
Answer: - Some helpful tips for resolving issues with ASCII serial communications over RS485 using COMMREQ functions include verifying the wiring setup, checking the configuration settings for baud rate and parity, ensuring proper termination resistors are in place, and reviewing the COMMREQ function parameters for accuracy.
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