V17 Can't write tags to PLC, Internal Works Fine

I have done this before. Even in trainning (but unfortunately lost my .zap16 from those) but I am not able to make it work right now. 

This in not the actual project anymore, because I decided to create a test project to troubleshoot it and isolate the problem. 

I created a new project with an S7 1200 1214C AC/DC/Rly, and I have this physical PLC connected to my PC. 

I created 2 Global DBs and a few tags, made sure everything is accessible through HMI/OPC UA, whatever.

Created the Unified PC, IE General connection, connected both. Configured all IP addresses and everything. Added a Local User, added ALL permissions and rights. 

New Screen, buttons, a few fields, everything. When trying to WRITE to the PLC DBs, it won't. 

TraceViewer shows this:

Message is: session: 0001, trace: FUNCTION_CALL Invoke failed (id=7, function='HMIRuntime->Tags->SysFct->InvertBitInTag', error=80000005)

Notice that the number 22 is shown fine, I manually added this value to the DB and it READs fine. I can't write on it, it blinks red and won't take the value, but TraceVewer shows nothing in that case. 

I created other DB, types of variables, but nothing really works. Reset PLC, Deleted IHM Runtime, redid everything in another PC. Heck, last week I thought it was a bug with Windows 11 and formatted and downgraded to Windows 10. 

Internal variables work fine, as expected. But when trying to write to PLC values it won't let me. 

I will leave a few of the config screens bellow if anyone can spot something obvious I left behind. 

Something strange that I stumbled accross during testing. 

If I Instead create a Unified Panel, instead of a PC, everything works. Exact same everything, as far as I can see. 

Really need help here. 

Check your security settings, and make sure that your Unified Login User does NOT have the "HMI Monitor Client" access right activated. 

This Right will overwrite the other acces rights and stop you from making changes to the PLC tags. 

Nubbi

Check your security settings, and make sure that your Unified Login User does NOT have the "HMI Monitor Client" access right activated. 

This Right will overwrite the other acces rights and stop you from making changes to the PLC tags. 

 I saw this in another thread and changed it in mine yesterday, without any luck. Made sure to trasnfer it on the pop up for downloading, but nothing changed

Hi Vinizuca,

Numerous improvements have been developed for WinCC Unified V16 with the Updates released (and even more for V17...).

Please try to upgrade to the latest WinCC Unified V16 Update via this link, and then make sure you only give the project user the highest (Administrator) permission, not all of them.

Also, make sure that the PLC is not protected against HMI access and that, in the case of IO fields, the format is Input/Output.

 Hi! Thank you very much, this answer help me a lot.

Nubbi

Check your security settings, and make sure that your Unified Login User does NOT have the "HMI Monitor Client" access right activated. 

This Right will overwrite the other acces rights and stop you from making changes to the PLC tags. 

Nubbi

Check your security settings, and make sure that your Unified Login User does NOT have the "HMI Monitor Client" access right activated. 

This Right will overwrite the other acces rights and stop you from making changes to the PLC tags. 

 Thank you! Your hint was very helpful.