Hi,

I've got three independent machines that have identical hardware configuration:

• TP1200 Comfort (6AV2 124-0MC01-0AX0) 
• CPU 1516F-3 PN/DP (6ES7 516-3FN02-0AB0)

 All the HMIs are dropping communication (not all the same time), and the PLCs stop receiving any commands from them, which can only be fixed by power cycling the panels.

So far, I've tried the following:

• Re compiled and re downloaded HMI's program,
• Replaced PROFINET cables,
• Updated HMI's firmware to the latest version,
• Updated CPU's firmware to the latest version,
• Updated HMI's system and runtime clocks,
• Set HMI time synchronization as Slave mode.

None of them solved the problem.

Any ideas on what should be done?

The HMI's image version is: V17.00.00.08_05.01.

The fault that shows in the buffer is: "System initiated session termination" (picture attached). I couldn't find any other related fault at the same time the HMI drops comms.

Thank you. I will check both procedures.

Yes, we do have Alarm View for system alarms, but, unfortunately, the HMI doesn't show any messages when that happens.

This problem does not happen very often, usually occurs once every two or three weeks. Just wanted to rule everything out before looking at replacing the HMI.

Will try to get more snapshots from the PLC and HMI next time.

The diagnostic buffer mentions a security issue. @Wizard provided information that relates to that. It would however be helpful if you mention which security settings are set on the devices. Mention also the firmware version of your CPU. 

The other missing point is the devices that are connected to each other. Is there the possibility that some device links onto the physical network that has the same network addressing or Profinet name?