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I'm having a problem updating the Digital Outputs through the code. If I monitor the outputs in Online-PLC Configuration the squares turn blue as if the output is switching, but it doesn't.
If I use the Online-PLC Configuration (clicking on the blue square) to switch the outputs the turn on/off correctly. Also when I do this the ones already turned On by the code switch.
Is there something needed in the code to force an update of the digital outs?
I'm running CodeSys 2.3 on a Kontron ThinkIO-P.
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Outputs will turn on and off if you force them only if the variable is not being called any where else in the code. If a variable is being called in the code, ie the variable bMotorStart := false; and you try to force it from the PLC configuration then it will never turn on. Forcing outputs from variables being called in code as far as I am aware of is an art. Normally the control code is broken into at least three sections. Input section, control section, output section. When there is a need to force the outputs then a bit is set in such a way that no longer calls that output variable so you can manually turn it on and off.
if (bForceMode = False) then
bMotorStart := bStartEnable;
end_if
To force the variable bMotorStart set bForceMode = True;
As for your outputs not coming on perform a global search for the variable and make sure it's not being called some where else in your code. There is also an option in Project-Options-Build-Multiple write access on outputs menu to force CoDeSys to check for this situation at compile time an report in the message window.
Hope this helps.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
I'm having a problem updating the Digital Outputs through the code. If I monitor the outputs in Online-PLC Configuration the squares turn blue as if the output is switching, but it doesn't.
If I use the Online-PLC Configuration (clicking on the blue square) to switch the outputs the turn on/off correctly. Also when I do this the ones already turned On by the code switch.
Is there something needed in the code to force an update of the digital outs?
I'm running CodeSys 2.3 on a Kontron ThinkIO-P.
Outputs will turn on and off if you force them only if the variable is not being called any where else in the code. If a variable is being called in the code, ie the variable bMotorStart := false; and you try to force it from the PLC configuration then it will never turn on. Forcing outputs from variables being called in code as far as I am aware of is an art. Normally the control code is broken into at least three sections. Input section, control section, output section. When there is a need to force the outputs then a bit is set in such a way that no longer calls that output variable so you can manually turn it on and off.
if (bForceMode = False) then
bMotorStart := bStartEnable;
end_if
To force the variable bMotorStart set bForceMode = True;
As for your outputs not coming on perform a global search for the variable and make sure it's not being called some where else in your code. There is also an option in Project-Options-Build-Multiple write access on outputs menu to force CoDeSys to check for this situation at compile time an report in the message window.
Hope this helps.
Thanks for the response.
It turns out there was a hardware problem with the PLC and a certain combination of IO modules.
I have since switched to a Moeller PLC and the same code works fine.