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Use STRING datatype with IEC61131 F_SEL block [message #1733888]

Wed, 01 June 2016 16:36

Eclipse User

Hi,

I'd like to switch between two string constants, depending on a BOOL value. That's why the F_SEL block was my first guess. Both inputs are of datatype ANY so i thought i can connect a STRING there. When I try to enter the string constants directly in the F_SEL properties, the IDE tells me, that this is not allowed. Also connecting other FB with STRING outputs to the F_SEL does not work.
Is there any easy way to achieve this, without having to create my own F_SEL_STRING block and compile it into FORTE?

Thanks
Herwig

Re: Use STRING datatype with IEC61131 F_SEL block [message #1733893 is a reply to message #1733888]

Wed, 01 June 2016 17:36

Eclipse User

HI,

could you be more specific on the error message. You should be able to put string constants on F_SEL. However as it is an ANY input you have to add the type information to your constants following the IEC 61131-3 literal conventions. For strings this means that you have to add STRING# upfront (e.g, STRING#MYSTRingconstant).

Also connecting strings should work. Could you say more on what is not working there?

Alois

Re: Use STRING datatype with IEC61131 F_SEL block [message #1733912 is a reply to message #1733893]

Thu, 02 June 2016 03:55

Eclipse User

Hi Alois,
thanks for your feedback. I did not use the STRING#, so this explains why i was not able to set the string constant in the F_SEL directly. I will try this on the weekend. When trying to connect the output of a CONCAT block with the F_SEL input I see a small prohibition sign and the wire is not connected and disappears when i release the mouse button.

greetings
Herwig

Re: Use STRING datatype with IEC61131 F_SEL block [message #1733936 is a reply to message #1733912]

Thu, 02 June 2016 06:39

Eclipse User

Hi Herwig,

thanks for the clarification. The problem with the CONCAT block is that it has as in and outputs ANY_STRINGS which have to be typed as well. Unfortunately we are currently not very good in propagating the type through a network. So for now you would need to insert a STRING2STRING FB between CONCAT and F_SEL. I know this is ugly and I really want to have this gone.

The CONCAT function is maybe better used in algorithms there I think it will also be more efficient as the compiler can optimize away some overhead.

Alois

Re: Use STRING datatype with IEC61131 F_SEL block [message #1734136 is a reply to message #1733936]

Sat, 04 June 2016 14:23

Eclipse User

Hi Alois,
the string constant STRING#MyString works now.
I cannot find a STRING2STRING block in the library, at least it is not part of the IEC61131-3 conversion blocks. I can find a STRING_TO_WSTRING converter

kind regards
Herwig

Re: Use STRING datatype with IEC61131 F_SEL block [message #1734185 is a reply to message #1734136]

Sun, 05 June 2016 17:32

Eclipse User

STRING2STRING is in the conversion library (Edit: which is outside of the IEC 61131-3 lib).

Cheers,
Alois

[Updated on: Sun, 05 June 2016 17:32] by Moderator

Re: Use STRING datatype with IEC61131 F_SEL block [message #1734284 is a reply to message #1734185]

Mon, 06 June 2016 14:18

Eclipse User

Thanks, Alois

it's working now, I overlooked the "convert" folder in the type library Embarrassed

and only searched within the IEC61131-3 converters.
The STRING2STRING after the F_SEL did the trick.
greetings
Herwig

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