Scheduled Task every start

GoodMorning,

I notice that every plc's start, HMI executes scheduled tasks triggered by variable ( like attachments)

I hoped that it execute only on a variable edge

Someone can help me?

Thanks 

Hi AndreaLari,

The HMI system internally caches the tag values and compares them to the read PLC values to detect a changed tag. At startup, these internal values are initialized with the default values. Therefore, a changed value will be detected the first time the PLC tag is read as long as the PLC value does not match the default value.

I think the use of tag persistence should help to overcome this problem. Or you can do some scripting to abort the task within a limited time after startup.

Kind regards
Stefan

Thanks Stefan for your answer but i can't understand how can help me variable persistency.

It can be set only for internal variables and not for variables from PLC connection.

Can you explain me?

Thanks 

Hi AndreaLari,

AndreaLari

Thanks Stefan for your answer but i can't understand how can help me variable persistency.

It can be set only for internal variables and not for variables from PLC connection.

Can you explain me?

Sorry, I did not consider the fact that persistence is only for internal tags when I wrote my answer.

But hopefully you understand the root cause of your problem and rdoliveira's answer will help you.

Kind regards
Stefan

Hi Rdoliveira

i already did what you say. 

But i believe that is not correct for well working. If you say that trigger is the value change of variable you can't execute at the start of program 

Anyway thanks for help