Hello,

Please check the following links. Perhaps it might help you.

Connecting older HMI to S7-1500/1200 with newer firmware

Because your panel has image v15.1 the following link is not of use 

No connection to PLC after WinCC Panel Images V17 Update 6

Please check:

In WinCC (TIA Portal), how do you configure a connection between WinCC Runtime Advanced or HMI Panel and an S7 controller over Industrial Ethernet (PROFINET)?

(In simulation you say it is working?)

Please program an Alarm view in HMI project to show the Alarm buffer. Check if you see some system messages,

Best regards,

Wizard

Hello LPK007

Which Security settings do you use in your PLC?

Do you have activated Put&Get communication or do you have acrivatedd the Secure HMI communication?

Do you have the PLC and the HMI in the same project (or do you use a manual HMI connection)?

I would recommend upgradeing the HMI to latest version and OS Version.

Bye Murof