How do I fix ABCLX driver connection issues with Citect SCADA


03 October 2021


There are a few common fixes for basic communication and connection problems with the ABCLX driver within Citect SCADA. Implementing these fixes will rectify most basic issues.


  • Citect SCADA 8.2 and below
  • ABCLX driver


  • #BAD values in tags
  • #COMM values in tags
  • Driver offline error
  • Communication problems between ABCLX driver and Citect SCADA


There are numerous common fixes that may work to fix the communication issues. Please check after each action to see if the issue has been resolved.

The first action to try to fix the issue is to make sure you are using the most recent version of the ABCLX driver and TCPIP driver. Additionally, it is best practice to update to the most recent patch of the Citect SCADA version you are using. All of these updates can be found in the AVEVA website under Drivers and Products respectively.

The second action to try is to implement the following INI parameters. It is important to enter the last 2 parameters exactly as they appear here, as other combinations can often cause issues to arise with the driver.

ConnTimeout = 10000
ForwardOpenPoolSize = 8
LostMsgRetry = 6
LostMsgtimeout = 2000
MissedPollTolerance = 10
ScanRate = 1000
OptimizeUserDefinedDataType = 1
FailOnBadData = 0


The third action is to clear out the #BAD tags using the instructions in the following TechNote (TN6461). This is a standard process for clearing #BAD tags.

The fourth action is to test the PLC tags for any restrictions on their reading and writing function. The following TechNote (TN8142) outlines the steps to do this.


If none of the above actions work to fix the issue, then the communications issues must have a non-standard cause. It is advised that you review your driver and tag configuration, topology settings, and contact your support provider for further troubleshooting instruction.