KEPServerEX 6 is slow and loses connection with Allen-Bradley PLC

[David.V]

Good day,

I'am currently working on project that involves connecting 2 SCADA systems/servers (Cimplicity software from GE) with 5 Allen-Bradley PLCs (1x 1756-L85E, 4x 1756-L81E) via OPC-UA. 

Setup; There are 2 SCADA servers (A and B), they both have Cimplicity running with redundancy setup A=Master, B=Backup. Each server has KEPServerEX 6 installed on it with the same connection setup.

PLCs: There is the main PLC L85E that takes care of almost everything and 4 smaller once (L81E) for some fast calculations and motions.

The biggest problem that I have now is with the communication with the main PLC. The smaller once have no problems. Just having one server running gives us problems. Kepserver is losing it's connection with the main PLC almost every time we are doing  online changes in the PLC logic (Socket error occurred receiving data. Error=10054,..An existing connection was forcibly closed by the remote host). 

Second problem is that it takes 2-5 seconds to see something change on SCADA after pressing a button (for example a color). When I click on SCADA I can see the values changing in the PLC within 200-500 ms + the cycle time, it sends the values out of the PLC within 1 sec. When I change screens or open pop-ups it happens with no delay as this is happening internally in Cimplicity. It's just getting the data from the PLC to SCADA trough Kepserver that takes waaaayyy to long.

Those problems get even worse when both servers are running as there are 2 Kepserver project trying to get data from the PLC.

Does anyone know what might cause those issues? Scan Mode, Tag generation...

The main PLC has according to the property window 1741003 static tags. Don't know is that is high but it looks like it is. The smaller PLCs have around 21000 static tags.

Thank you for reading all the way to the end.

Kind regards,

David

[cmorehead · Accepted solution]

@vd_10522170,

It initially sounds like you have multiple devices configured under a singular channel. Please take a look at the knowledge base article in the following link. You can access the article my kepware login credentials:

Article - CS292754 - Configuration project performance optimization in PTC Kepware Products

If the article does not resolve the issue, you should open a support ticket with the Kepware team to troubleshoot your specific architecture. Here is a link to the login page where a support ticket can be opened:

Log In | My Kepware

Thanks,

*Chris

[David.V]

Hi Chris,

First I wasn't in favor of changing to multiple channels because I didn't knew how it will affect my SCADA tags. Turns out is was easy to do that in the SCADA software. and even easier in Kepware.

Splitting the PLCs in over multiple channels solved the communication lost problem to some degree. I haven't seen the main PLC losing its connection. I however see now that if I activate the Auto-Demote function on both kepservers: One Kepserver will communicate with SCADA and get data from the PLCs. While the other one (active but not used by SCADA) will always give timeout/demote. Not a problem. If the first kepserver fails the other one takes over with no problems. 

The second issue with SCADA speed was not a cause of kepserver. That is a SCADA issue. To much data from the PLC is requested by SCADA. Can't do much about it (hardware limitations).

Thank you.