Modbus Failure On State sending Get More About It By Logging

General
1

I am using a USB to RS485 converter (Waveshare) on my Raspberry Pi 4 to query two power meter (SDM630) via Modbus RTU using the Modbus-Flex-Getter. Everything works fine and stable without any errors over days as long as I don't touch the Flow (and especially the Flex-Getter-Node).

However if I am changing anything in the Flex-Getter-Node or in the Flow which sometimes causes the Flex-Getter-Node to do a reconnect, I get the following error messages:
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The only thing I can do to get the Modbus communication working again is to restart Node-Red. It's not a big deal as it works perfectly fine if I don't touch the Flow, it's a somewhat annoying behavior regardless and I don't know where to start to debug this.

Here are my settings:

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Raspberry Pi 4
Debian GNU/Linux 11 (bullseye)
Linux: 6.1.21-v8+

Node-Red: 3.1.3
node-red-contrib-modbus: 5.27.2
NodeJs: v20.11.0

2

Nodejs version 20 is not listed as tested / compatible with the Modbus nodes and some issue was reported on Github page (source)

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try downgrading to Node version 18

If you want to further test before downgrading nodejs .. try to stop Node-red and run it with command
DEBUG=contribModbus*,modbus-serial node-red -v

this will give you a more detailed log in the terminal, of each of the Modbus nodes actions (source)

1 Like
3

Downgrading to NodeJS 18 did the trick! Now the Flex-Getter-Node is reconnecting properly without having to restart Node-Red first! Thanks a lot! :slight_smile:

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