Hello,
I’m using a Siemens S7-1200 PLC (CPU 1214C DC/DC/Rly) and a KTP700 Basic PN HMI. The communication is set up via PROFINET.

I’ve created an HMI tag (e.g., Tag_1) for a lamp animation. I assigned it to the correct PLC tag (e.g., %M0.0) and connected it through the HMI connection to the PLC (Rack 0, Slot 1, IP 192.168.0.1). HMI IP is different and in the same subnet (e.g., 192.168.0.2).

However, when I run the HMI (or RT Simulator), I get the error:

Tag Tag_1: value could not be written to the PLC

And also:

Connection disconnected: HMI_Connection_1, Station 192.168.0.1, Rack 0, Slot 1

What could be the reason this tag is not writing to the PLC?

• Both HMI and PLC compile and download successfully
• The PLC is in RUN mode
• Connection in HMI device is set to SIMATIC S7-1200 → PROFINET(X1)
• I can ping the PLC from PC
• Tag address is valid and available in the PLC

Please help me resolve this issue.
Thank you!

Hello,

Please have a look at the following link:

No connection to PLC after WinCC Panel Images V17 Update 6

Check the Date and time on the panel. 

Best regards,

Wizard