Error Writing to KepServerEX Simulator with Node-red

[MM_14203880]

I have no problem in reading Kepware simulator from address R0001 (which self incrementing) from node-red, but unable to write into address K0001 or S0001 in node-red. Any advice will be much appreciated ? The moment i started to write, the node-red exited!.

ns=2;s=SimulatorChannel.SimulatorDevice.MyWriteTag

[MKhatri]

Greetings,

Ensure that tags K0001 and S0001 in Kepware are set to Read/Write under Client Access in tag properties. This allows Node-RED to perform write operations without crashing.

Regards,
Mohit

[pshashipreetham]

Hi,

If you can read from the KepServerEX Simulator but Node-RED crashes when writing, the issue is usually with the OPC UA node configuration or tag permissions. Here’s what you need to check:

1. Tag Permissions in KepServerEX

   • Open your Simulator Channel → Device → Tag in KepServerEX.

   • Make sure the tag you’re trying to write to is configured as Read/Write, not Read-Only.

   • Test the write directly from KepServerEX Quick Client first. If that fails too, it’s a tag configuration issue.

2. Node-RED OPC UA Write Node Setup

   • The Node-RED OPC UA “write” node should have the correct namespace and node ID. Example:

     ns=2;s=SimulatorChannel.SimulatorDevice.MyWriteTag
     

   • Double-check that this matches exactly with the tag path in KepServerEX (case-sensitive).

3. Data Type Match

   • Node-RED must send a value of the same data type as defined in KepServerEX.

   • For example, if your tag is Int16, send a numeric value, not a string.

   • Mismatched types will cause the OPC UA client (Node-RED) to exit or fail.

4. User Access Level

   • If you’re connecting with security policies enabled, ensure the user credentials have write access in KepServerEX.

   • Under Project Properties → OPC UA → Users and Permissions, verify the account used by Node-RED is allowed to write.

5. Test Using UaExpert

   • Try writing to the same tag from UaExpert. If it works, the problem is in Node-RED configuration.

   • If it fails in UaExpert too, it’s definitely a KepServerEX tag or permission issue.

Once tag permissions, namespace, and data types are aligned, Node-RED will write successfully without exiting.

Thanks,