Skip to main content
D
Dinael3-Newcomer
3-Newcomer
April 15, 2026
Question

KepserverEX - OPC UA / DA stability issues

  • April 15, 2026
  • 1 reply
  • 66 views

Hi, 

I have a customer that is using Kepware Server for OPC DA / OPC UA / OPC DA communication between two systems. 
At the moment we are having issues with certain slow updating tags (booleans and integers) that freezes and are not updated between the two systems. 
Continuous updating values are no issue... 

The issue seem to be that the tags gets timed out and are not correctly mirrored between the systems. 

If we create local subscriptions on the KepServer node on the actual tags the error seem to disappear. 

Is there a way to configure kepware to establish the subscription to the source tags regardless of the client status? 
We cant find any correlating error messages in kepware. 

1 reply

M
MKhatriCommunity Manager
Support
June 22, 2026

Greeting Dinael,
 

  • Issue likely due to Kepware not maintaining active subscriptions when no OPC client is connected.

  • By default, Kepware updates tags only on active client demand (Subscription-based) → idle tags may scan slowly or stop, causing timeout/mirroring issues.

  • Creating local subscriptions works because it forces Kepware to continuously poll/update tags ✅

  • Recommended solutions:

    • Enable “Scan Mode = Respect Client-Specified Scan Rate” → change to “Request Data No Faster Than Scan Rate” (forces continuous polling)
    • Set Scan Rate manually on device/tags (e.g., 100–500 ms)
    • Enable “Always Active” option for tags/groups (if applicable)
    • Use Advanced Tags / Link Tags to maintain internal subscription

  • Alternative:

    • Use OPC UA subscriptions with keep-alive settings tuned (avoid timeout)

  • Summary:

    • Yes—configure Kepware to continuously scan tags independent of client connection to avoid freezing values.
Terms & ConditionsAccessibility statement