RT block not resetting when connected to a TRIG block

Issue

In some cases, if the block connected to reset (rs) of a Run Time (RT) block is a trigger (TRIG) block, the RT block will never reset.

Product Line

TAC Vista, SmartStruxure Solution

Environment

Menta

Xenta

Cause

If the order of the TRIG and RT block is not correct, the RT block will miss the pulse from the TRIG block. This only seems to happen when the block connected to the TRIG block is a PV block such as PVB. If the block connected to the TRIG block is e.g. a physical input such as DI the problem doesn't occur.

Resolution

There are two solutions to this problem


Solution 1: Create the blocks in the correct order

First create the "TRIG" block and then create the "RT" block. If you already have both, then delete the "RT" block, save and create a new "RT" block.


Solution 2: Add a DELB block

Add a "DELB" block before the "TRIG" block. This will make the "TRIG" block hold the signal long enough for the "RT" block to detect it.