How to init bool array with TRUE in ST (Twincat2)?

Question

How to init a boolean array in Structured Text (Twincat 2) with TRUE?

For example like this:

VAR

    a_referenz_array : ARRAY[0..2] OF BOOL := TRUE, FALSE ; (* This does not work !! *)

END_VAR

to1234go · Answer 1 · 2019-09-06T12:14:50.897

0

You can use FOR loop in your initialisation's section (it implements once on starting PLC):

FOR I:=0 TO 2 DO
   a_referenz_array[I]:=TRUE;
END_FOR

edited Sep 06 '19 at 12:14

answered Sep 06 '19 at 12:09

to1234go

Yes, this is the solution which I've been currently using. However, how about to do it in the declaration part? – Richard Teubner Sep 06 '19 at 12:41

score 0 · Answer 2 · answered Sep 06 '19 at 13:02

0

In TwinCAT2: arr1 : ARRAY [1..2] OF BOOL := TRUE,FALSE;

TwinCAT3: arr1 : ARRAY [1..2] OF BOOL := [TRUE,FALSE];

Edit, should have checked your question more properly. This works in TwinCAT3, obviously not in TwinCAT2 :-)

answered Sep 06 '19 at 13:02

Jakob

yeah, I tried both in TwinCat2 and both are not working. Interesting, that it works in TwinCat3. – Richard Teubner Sep 06 '19 at 13:54

pboedker · Answer 3 · 2019-09-12T07:42:49.370

Your code WILL work as intended, I tested it in TC2. But there are a couple of issues with it that could confuse while testing...

Your array has a size of 3 booleans but you only initialize 2. This means that only index 0 and 1 will be initialized and depending on the rest of your code you might discover it or not.
The array will only be initialized following a PLC reset, so changing the code, recompiling and monitoring it online might not have any effect at all. You should send a reset command to the PLC and then re-run the program.
My TC2 version is 2.11.2301... It's a long shot, but if yours is very much older, that could be the cause too.

Your code:

VAR
    a_referenz_array : ARRAY[0..2] OF BOOL := TRUE, FALSE ;
END_VAR

3 Answers3