When a DELR or DELI block is used with a comparison operator to detect a change of value in the output of a function block, the output of the comparison operator should go ON for one scan when the source output value changes. If the source function block is a PVR or PVI this does not occur. For example:
This code does not work
This code works
StruxureWare Building Operation version 1.3.0 or earlier
Function Block Editor
There is a defect in StruxureWare Building Operation version 1.3.0 or earlier that causes this behaviour when writing to a public PVR or PVI block in a Function Block Program in the ES or AS directly from the Workstation.
This defect has been logged with Quality Center and will be fixed in SmartStruxure version 1.4.0
Meanwhile, the workaround is to insert any compatible block immediately after the PVR or PVI. For example:
The inserted block could be an operator, an expression block or even another DELR.
Although the workaround works, the preferred practice for new applications would be to replace the PVR with a RI and bind the RI to an Analog Value in the ES or AS.
This defect does not occur in Menta programs in Xenta controllers, including those written in the SmartStruxure Menta Editor.