Screen change on PLC connection

Hello people,

my question this time is the following, does any of you know how I can trigger a screen change on my MTP1000 Unified Basic when it connects to the PLC?

I usually put an invisible button on the start page, when it's pressed it will change screen to the main menu.

Sometimes, on not unified HMIs, I also managed to trigger the change using the PLC's "AlwaysTRUE" merker, when the HMIs connect to the PLC, they detect the "change" of the merker and move screen. It does not work anymore it seems and definetely not on Unfiied HMIs. 

On the unified basic I tried using a script, but i wouldn't know where and when to call it, because "hmiruntime.UI.." in not usable on scheduled tasks, it gives me error.

If you also know a way to do it on not unified HMIs I'll be very grateful.

Thank you

The scheduled tasks are running at server level, the hmi visualization is a client session. Because of this reason it is not possible to directly trigger a screen change from scheduled tasks.

The way I would do it would be to run a script periodically with an invisible object, or maybe a background property on your home screen.

it is possible to read the quality code of a tag

https://support.industry.siemens.com/cs/us/en/view/109813308/151802265867

I would read the quality code of a tag, detect a change from bad to good and save the quality in an hmi tag

in pseudocode: 

let newQuality = Tags("plcTag").QualityCode;
let oldQuality = Tags("hmiTag_memory").Read(); //this is a bool in global hmi tags

if oldQuality = 0 and newQuality = good { //good would be some sort of mask
    screenChange;
}

Tags.("hmiTag_memory").write(newQuality == good);

Hi DM_Mat_95!

In the Comfort, for example, there were area pointers that allowed, for example, a screen change from the PLC. In Unified as such there are no area pointers. Maybe you can use this FAQ: since they are the alternatives to the area pointer:

-> Alternatives to the area pointer for Unified Panel

https://support.industry.siemens.com/cs/bd/en/view/109794243

Thank you everyone,

I managed to do it like this: