TN IT292 Fix for when a Discrete bit continuously fails to Set or Unset in InTouch

Description

This article from InSource shows how to possibly fix the InTouch application when a Discrete tag continuously fails to Set (1) or Unset (0).

• Author: Rufus Handsome
• Published: 12/10/2017
• Applies to: Wonderware InTouch 2014 and Higher

Details

If the InTouch node is functioning as a Tag Server, there have been cases where some Discrete tags that have been configured to be "Direct" actions, fail to be unset to 0 when the button is released. Adding ForceWriteForDiscreteIOTags=1 to the InTouch.ini, located in the application’s directory resolved the issue. Apparently this has been a lingering issue for several InTouch releases. It seems more likely to be an issue when using InTouch as a tagserver. The problem can occur after upgrading from DAServers to OI Servers.

The issue is due to timing. The button thinks it wrote the value, but it was not processed downstream. Without this setting, InTouch will not re-write a value to a tag that it thinks is already set. With this setting, it will re-write even if it thinks the value is OK. There is some timing issue with InTouch, ABCIP, Suitelink, and/or the PLC that only makes this issue appear in rare cases. Direct buttons and InTouch-as-tagserver situations are most vulnerable. Remote IO references can also increase the chances of seeing this. There must be some timing difference between DASABCIP and OI ABCIP or if they upgraded server hardware, overall timing could have changed.

This seems to only apply when InTouch is communicating via Suitelink. ArchestrA graphics communicate differently and don’t have this issue.