Modbus Serial (RS485) Write Failure - Node Red


I have followed Modbus serial with Node-RED and was successful upon reading data with the recommended hardware and a real device.

However, every time I try to write to a coil, it always fails. I have set the payload as a buffer and still fails. Has anyone, gotten a write command to work?

Thanks in advance,

Can you flesh things out a little more for us?

What device are you read/writing to?
What serial port are you using (module or USB)?
What Node-RED nodes are you using?
Are you able to read/write to the device using modscan32?


So you are not a mind reader lol.

Below are some more details…

Trying to write to the below entry.

I am going to try using modscan32 now.

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Ok. I think I understand the problem.

Since the device is not actively collecting data the value is 0 and that coil is used to reset a total. Using modscan32 and viewing the output, I get the exact error message back. I have a feeling when this device goes into the field and collect real data, I will be able to reset that value.

Once this device is installed, I will re-run this exact test and report back.

Thank You.

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