TIA Portal V15.1, 1515F PLC, TP900 Comfort HMI

I am trying to execute a faceplate script using the ChangeValue event on a property of the faceplate.

When I assign the property to an internal HMI tag which is set via a button on the HMI, the script will not execute.

When I assign the property to a PLC tag which I manipulate manually, the script will execute.

I've tried multiple HMI internal tags and multiple tags linked to the PLC, with the same result. Screenshots are attached.

Does anyone know what is going on here and have a solution?

Thanks and regards,

Angus

Hello Angus,

 Hello Prof. Frink, thanks for your reply and thanks for the tips and tricks link. I'll have a read through the other points there as well. 

I'm not certain whether this restriction applies to my situation or not. A literal reading of the explanation  suggests not, as it's referring to mapping one HMI tag to another HMI tag which then triggers the script.

In my case, I am only using one HMI tag to trigger the script. The value of the HMI tag is set via a click script on a button. The HMI tag is assigned to the dynamization of a faceplate instance property. The faceplate property has a ChangeValue event configured which triggers the scrip. The script itself does then set a faceplate tag, but this is after the script is triggered rather than before. 

My understanding of the restriction as described:

HMI Tag -> HMI tag -> Faceplate property -> ChangeValue Event -> Calls faceplate function... (NOT ALLOWED)

What I am doing:

Button Click Script -> sets Internal HMI Tag -> Faceplate Property -> ChangeValue Event -> Calls faceplate function -> sets faceplate tag.

Do you think  this restriction would apply to my scenario?

If the restriction does apply, is there a way to switch it off? It really shouldn't be necessary to have to map a tag into the PLC and back just to trigger a function from a button.

Prof. Frink

Hello Angus,

Tips and tricks for creating scripts in WinCC (TIA Portal) 

Why is a script, which is configured to occur in the event of a "change in value" of an internal tag, not executed?

If you use an internal tag to influence another internal tag, via which, for example, a script is executed (a change in value, for instance), then a safety mechanism prevents this function from being executed.

This safety function prevents scripts repeatedly calling each other in a loopback.

Example

In the Properties of the internal tag "HMI_Tag_01", a bit is set for the "Change in value" event in the internal tag "HMI_Tag_02".

At this second internal tag "HMI_Tag_02" a script is called through the Properties for the "Change in value" event.

Result: The script is not executed.

Remedy

Use an external tag which is linked to a controller. Please note that by using an external tag you circumvent the safety mechanism described above. This can lead to problems in Runtime.

Regards,

Frink

Hello Angus,

you cannot use the event "ChangeValue" of an internal tag to call a script.

Actually this issue was already subject of some posts in the forum and in my opinion it is not possible to deactivate the safety mechanism. You have to use a PLC tag if you want to use the event "ChangeValue".

Regards,

Frink

 Ok, thanks for the confirmation. Much appreciated.

Cheers,

Angus

Prof. Frink

Hello Angus,

you cannot use the event "ChangeValue" of an internal tag to call a script.

Actually this issue was already subject of some posts in the forum and in my opinion it is not possible to deactivate the safety mechanism. You have to use a PLC tag if you want to use the event "ChangeValue".

Regards,

Frink