Hello everyone, has anyone attempted to establish communication between a Schneider PM800 and a ML1400 PLC using rs485? I am encountering a problem where the local processor is receiving a message timeout. The wiring setup involves connecting terminal 20 (+) of the PM800 to channel 0 labeled B on an adapter, and terminal 19 (-) to Label A. Additionally, terminal 18 of the PM800 (possibly com) is connected to Com on the ML1400 adapter. In the PM800 settings, the address is set to node 4mbrtubr with a baud rate of 9600 and no parity. I have attached a configuration snippet for the PLC. Currently, I am trying to read a single piece of data and my message setup is as follows: MB Cmd - read input register 3xxxx, size 1, data table n111:0, MB Data address: 1123, and Slave node: 4. This is my first time working with rs485 communication.
MiLo28 asked if anyone has tried connecting a Schneider PM800 to a ML1400 via rs485. They are experiencing a message timeout issue in the local processor. The wiring setup includes terminal 20 (+) in PM800 connected to Channel 0 B, terminal 19 (-) in PM800 connected to Label A, and terminal 18 (COM) in PM800 connected to COM in the ML1400 adapter. PM800 settings include address node 4mbrtubr, baud rate 9600, and parity none. The message being sent is to read input register 3xxxx with a data size of 1. After troubleshooting, the issue was found to be related to the wiring and has been resolved.
Hi there! It seems like you have your configuration mostly correct, but troubleshooting communication setups can be like trying to find a needle in a haystack at times! Firstly, make sure your termination resistance on both ends of the RS485 network is set properly. Secondly, verify the settings on PM800 - the parity should match the one you've set on your ML1400. This mismatch could cause signal errors leading to message timeouts. Lastly, double-check your Modbus addressing. Although the PM800 address is set to node 4, it's worth remembering that Modbus address counting starts from zero, so it might be seeing this as node 5. Always cross-verify these details, no matter how minute they may seem! Good luck!
Hey there, I've worked with Schneider PM800s and ML1400 PLCs before so maybe I can offer some help. It sounds like your basic hardware setup and RS485 wiring are fine, so that's a start. I would suggest firstly checking your MODBUS command setup, because sometimes a simple typo can lead to communication timeouts. Ensure that you've got the correct data address and that the reading size is correct within the message setup. Also double-check the baud rate – while you said it's set to 9600, and this is pretty standard, it wouldn't hurt to cross-verify that this is correct on both devices. It's crucial that your baud rate, parity, and stop bits match on both your PLC and PM800. Hopefully this might clear up some things and you can successfully communicate! Let us know how it goes.
Hey there, your setup seems alright for the most part. However, I'd suggest double-checking your wiring scheme. Make sure there's no inversion in your A and B line connections between both devices. A common issue with RS485 communication is that different manufacturers might have different labels for line A and B. As a rule of thumb, A is often (-) and B (+), but some manufacturers do the exact opposite. You should also ensure that your grounding is properly done, as RS485 performance can be seriously affected by improper grounding. Besides, verify the Modbus address you're trying to read, maybe you could attempt reading from a different Modbus data register to exclude any potential errors with the specific register you're querying. Last but not least, it might be helpful to use a Modbus tester tool to simulate your ML1400 responses before adjusting your PM800 accordingly. Hope this helps!
It seems like you've done a good job of setting up for the most part. One thing that comes to mind is checking your termination resistor. With RS485 communication, missing or incorrectly installed termination resistors often cause issues like message timeout. Termination resistors should ideally be placed at both ends of a cable to prevent signal reflections that can destabilize the communication. Also, verify the data rate on both the devices - in this case, both the Schneider PM800 and ML1400 PLC. They need to match exactly (in your case 9600). Lastly, your addressing seems right, but do cross-verify that the slave address (node) is correctly set to '4' on your PM800. Sometimes the smallest things could cause the biggest problems!
It sounds like you've done some thorough troubleshooting already! Have you double-checked the wiring and ensured that the polarity of your RS485 connections is correct? Additionally, ensure that there are no mismatches in the baud rate or settings between the PM800 and ML1400—sometimes a small discrepancy can cause those timeout issues. If possible, try using a different cable or adapter to rule out any hardware faults. Lastly, confirming that the slave address and Modbus function code are correctly specified in both your configurations could also help resolve the communication problems. Good luck, and let us know what you find!
It sounds like you're off to a solid start, but those timeouts can be tricky with RS485 setups. Just double-check that all your device settings match up, especially the baud rate and data format—any mismatch could cause communication issues. Also, make sure your wiring is correct and that there's no grounding issue, as this can sometimes result in interference. Lastly, consider using a tool like a Modbus simulator to test your setup independently from the PLC; it can help you pinpoint if the issue lies with the PM800 or the PLC side. Good luck, and let us know if you figure it out!
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Answer: 1. What could be causing a message timeout when trying to establish communication between a Schneider PM800 and a MicroLogix 1400 PLC using RS485? - Answer: A message timeout could be caused by issues such as incorrect wiring connections, incorrect settings in the PM800 or PLC, mismatched baud rates, or communication protocol errors.
Answer: - Answer: The wiring setup should involve connecting terminal 20 (+) of the PM800 to channel 0 B on the adapter, terminal 19 (-) to Label A, and terminal 18 of the PM800 to Com on the ML1400 adapter.
Answer: - Answer: In the PM800 settings, ensure the address is set correctly (e.g., node 4), baud rate is set to 9600, and no parity is selected. Verify that these settings match the configuration in the PLC.
Answer: - Answer: Configure the message setup in the PLC to specify the correct Modbus command (e.g., read input register), data table address, data size, data address, and slave node address to match the PM800 settings.
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