For Me to facing same problem, 

WIncc unified to PLC via S71200/1500 Communication, PLC Tags are read from absolute address (DBX.DBXX) and 

SOme times Communicating some times Not communicating between PLC and SCADA But network Ping is ok 

Suggest what to do, any Certificate related issue? or COnnectivity issue??

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Split from Can't connect with some PLC - V17.

Hello syedInt,

have you tried to look into the System Alarms to check those when no tags are read.

Best Regards,

Fred

It could be a certificate issue, make sure that HMI and PLC are synchronized (same date-time).

If you have them synchronized and you're still having the communication issue, check your certificate with the certificate manager available in PLC Hardware. Make sure it has a correct date range. If you make any change in this certificate, remember to rebuild everything and download again to PLC and HMI.

Check in Control Panel if S7Online is associated with the correct interface.

Hello syedlnt!

Did you manage to solve this connection problem? What did you do?

Celio_Goetten

Check in Control Panel if S7Online is associated with the correct interface.

 This was the answer for me, Thanks Celio.

Please try to discuss in English. This is an international community and we try to focus on one language. Posting in English will help you to interact with everyone else.

This is the translation of your post:

janci_chaves

That was it, a detail, but an important one.

Thanks, man.

Thank you and best regards,
The Helping Hand