# Modbus TCP connection to node red replying with errors
**URL:** https://discourse.nodered.org/t/modbus-tcp-connection-to-node-red-replying-with-errors/101241
**Category:** General
**Tags:** modbus
**Created:** [9 June 2026 20:31 UTC](https://discourse.nodered.org/t/modbus-tcp-connection-to-node-red-replying-with-errors/101241 "2026-06-09T20:31:17Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@joeltackie](https://discourse.nodered.org/u/joeltackie)
#### Post date: [9 June 2026 20:31 UTC](https://discourse.nodered.org/t/modbus-tcp-connection-to-node-red-replying-with-errors/101241/1 "2026-06-09T20:31:17Z")
I am to connect node-red to a modbus server on the same network (LAN)
Using node-red-contrib-modbus palette
I keep getting this error; As shown in image 1
{" **enc**":true,"type":"error","data":{"name":"Error","message":"Port Not Open","stack":"Error: Port Not Open\n at C:\Users\joelt\.node-red\node\_modules\node-red-contrib-modbus\modbus\maps\core\core\modbus-client-core.js:37:206"}}
I turned on Modbus debug, I started getting this response (As Shown in image 2)
9 Jun 20:17:46 - [warn] [modbus-read:db7e824f2db08ed8] Modbus Failure On State sending Get More About It By Logging
9 Jun 20:17:46 - [error] [modbus-read:db7e824f2db08ed8] Error: Port Not Open
now I tested my port too, windows saids its open! (image 3)
ComputerName : 192.168.0.20
RemoteAddress : 192.168.0.20
RemotePort : 502
InterfaceAlias : Wi-Fi
SourceAddress : 192.168.0.101
TcpTestSucceeded : True
when I try with modsims local modbus tcp and my device's modbus rtu it works perfectly
my configuration is as below
I am running on Node-Red 5 and NodeJS
v24.16.0 but latest versions
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### Author:  [@juntiedt](https://discourse.nodered.org/u/juntiedt)
#### Post date: [11 June 2026 21:16 UTC](https://discourse.nodered.org/t/modbus-tcp-connection-to-node-red-replying-with-errors/101241/2 "2026-06-11T21:16:38Z")
I had some problems with modbus. Could solve all problems with Gemini. Give it a try
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### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [9 September 2026 21:16 UTC](https://discourse.nodered.org/t/modbus-tcp-connection-to-node-red-replying-with-errors/101241/3 "2026-09-09T21:16:50Z")
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