Modbus TCP - Unexpected issue

Problem

• unexpected behavior

Current behavior

I’m currently setting-up some Modbus Read nodes to read-out some values via Modbus TCP from differente devices. For one of the devices (Lennox HVAC machine - ReadLennox node below) no issues at all, but I can’t read out any values from our PLC (Wago - ReadPLC node below). However I can read out both devices with a Modbus Poll tool on my PC using the same addresses.

I’m getting following messages from the ReadPLC node: PortNotOpenError: Port Not Open FSM Reset On State {"value":"failed","actions":[],"changed":true}

Expected behavior

Seeing that I’m able to read both Modbus slaves from a poll tool, I should be able to read out both slaves from the Modbus Read, that doesn’t seem to be the case. Any tips on how to fix this?

Test flow

[ { "id": "8c891858.890aa8", "type": "tab", "label": "Flow 2", "disabled": false, "info": "" }, { "id": "a221a0b3.b2558", "type": "modbus-read", "z": "8c891858.890aa8", "name": "ReadLennox", "topic": "", "showStatusActivities": false, "logIOActivities": false, "showErrors": false, "unitid": "110", "dataType": "HoldingRegister", "adr": "37", "quantity": "7", "rate": "5", "rateUnit": "s", "delayOnStart": false, "startDelayTime": "", "server": "7b4f9c2f.b0b814", "useIOFile": false, "ioFile": "", "useIOForPayload": false, "x": 150, "y": 80, "wires": [ [], [] ] }, { "id": "273fcc14.078734", "type": "modbus-read", "z": "8c891858.890aa8", "name": "ReadPLC", "topic": "", "showStatusActivities": false, "logIOActivities": false, "showErrors": false, "unitid": "14", "dataType": "HoldingRegister", "adr": "0", "quantity": "1", "rate": "5", "rateUnit": "s", "delayOnStart": false, "startDelayTime": "", "server": "9fecc378.d3287", "useIOFile": false, "ioFile": "", "useIOForPayload": false, "x": 140, "y": 140, "wires": [ [], [] ] }, { "id": "7b4f9c2f.b0b814", "type": "modbus-client", "z": "", "name": "LennoxA", "clienttype": "tcp", "bufferCommands": true, "stateLogEnabled": false, "tcpHost": "192.168.30.110", "tcpPort": "502", "tcpType": "DEFAULT", "serialPort": "/dev/ttyUSB", "serialType": "RTU-BUFFERD", "serialBaudrate": "9600", "serialDatabits": "8", "serialStopbits": "1", "serialParity": "none", "serialConnectionDelay": "100", "unit_id": 110, "commandDelay": 1, "clientTimeout": 1000, "reconnectOnTimeout": true, "reconnectTimeout": 2000, "parallelUnitIdsAllowed": true }, { "id": "9fecc378.d3287", "type": "modbus-client", "z": "", "name": "PLC", "clienttype": "tcp", "bufferCommands": true, "stateLogEnabled": false, "tcpHost": "192.168.30.14", "tcpPort": "502", "tcpType": "DEFAULT", "serialPort": "/dev/ttyUSB", "serialType": "RTU-BUFFERD", "serialBaudrate": "9600", "serialDatabits": "8", "serialStopbits": "1", "serialParity": "none", "serialConnectionDelay": "100", "unit_id": 14, "commandDelay": 1, "clientTimeout": 1000, "reconnectOnTimeout": true, "reconnectTimeout": 2000, "parallelUnitIdsAllowed": true } ]

Your Environment

Using via a Docker container, installed via nodered/node-red. Installed node-red-contrib-modbus 5.2.0 via the Palette Manager.

• Device

  • Docker 19.03.07

• Description of the connecting Modbus system:

  • Wago 750 PFC200

• node-red-contrib-modbus version: v5.2.0

• Node: (min. 10.x) node --version = v10.19.0

[schefa11]

Was my fault due to missing knowledge… .I have a Node-Red Installation on my Windows PC. Running the debug-mode in command prompt requires the corresponding environment variable: SET DEBUG=contribModbus*

Same for powershell: $env:DEBUG = “contribModbus*”

[biancode]

Please, test v5.4.0 and reopen with new information if the problem is not fixed.