Limitation for CONCAT WSTRING for more than two inputs?

Hello,

I have an issue if I used three WSTRING inputs at the CONCAT function in a FOR loop then the resulting WSTRING will have the limit around 1030-1050 characters.

In other words if i use the below code then isn't works correctly (#statMeasurementsString is WSTRING[3000], #statWorkString is Array[1..50] of WSTRING)

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Split from How many strings can you concatenate using SCL?.

GabyT

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 Do anybody know  if is a limitation for more than two inputs ?

It sounds a bit strange, I can't see why there would be such a limit unless it's a bug in the lower level firmware implementation of this function.

Do you have some full test cases separate from your application that show this?

You should be able to put them together pretty easily within an example FC using Constants and Temps.

e.g.

TEMP:

WStringResult1 : WSTRING;

WStringResult2 : WSTRING;

ComparesGood : bool;

CONSTANT:

WString1 : WSTRING#" .... a really long string...";

WString2 : WSTRING#" .... a really long string...";

WString3 : WSTRING#" .... a really long string...";

WStringResult1 := CONCAT(IN1:= WString1, IN2:= WString2);

WStringResult1 := CONCAT(IN1:= WStringResult1, IN2:=WString3);

WStringResult2 := CONCAT(IN1:=WString1, IN2:=WString2, IN3:=WString3);

ComparesGood := WStringResult1=WStringResult2;

Hello Bevan Weiss,

Thank you for your answer, for me as well it seems really strange. This is the reason why I posted this on the Forum 

Actually we tested on  two totally different projects (TIA V16 and TIA V18) and different PLC's (also on PLCSIM Advanced 4.0)  and the result was almost the same.

Do you tested your code with inputs longer than 1100 characters  and the resulting strings were equal ?

Please give me the PLC model and firmware used by you.

Thanks.

GabyT

GabyT

Hello Bevan Weiss,

Thank you for your answer, for me as well it seems really strange. This is the reason why I posted this on the Forum 

Actually we tested on  two totally different projects (TIA V16 and TIA V18) and different PLC's (also on PLCSIM Advanced 4.0)  and the result was almost the same.

Do you tested your code with inputs longer than 1100 characters  and the resulting strings were equal ?

Please give me the PLC model and firmware used by you.

Thanks.

GabyT

I never use WSTRING, they take up too much room, and if it's not cp1252 it's too hard for me to work my head around.

I apologise for doubting your situation however.

I've tested it with the image attached.  It's indeed pretty broken.  I'd suggest you raise it with Siemens as a bug (in the most trivial reproducible example you can provide, like I've shown... don't provide your whole project with millions of references to tags and expect them to trust you that you're not doing something weird.) 

PS: Sorry, I had originally tried to create TestStrings of 2000 characters, hence the FOR loop.  But then resized them to 1000 to try to get them into Temp before moving it all to a DB.  So the CONCAT on the build of the initial TestStrings 'stops' at 1000 (the defined size of the TestStrings).  Both ResultStrings are defined as WString[4000], the sum of the three TestStrings, plus some margin.