Communication issue between 800xa redundant connectivity servers and Redundanr AC500 PLCs
I am trying to establish communication between 800xA 6.0.3 and AC500 redundant PLCs via PLC connect and Codesys OPC server.
For the first few days, there was no issue with the communication between the two systems, however since yesterday the PLCconnect OPC browser takes a very long time to display the PLC tags and hangs after a while.
Even though the WinCodesysOPC.exe service and gateway server are running on both connectivity server, the OPC server fails to establish any connection with the PLCs. The .dwg_HA_ServerAlive tag takes a very long time to increment or gets stuck at some value and the counts restart from zero.
Once OPC browser hangs, after trying to close it, it shows the following error
"Method '~' of object '~' failed
To resolve the issue I have tried the following
1)Disable and enable the OPCda service providers
2)Delete the service providers and recreate them and assign the ProgID
3)Stop the system,stop the OPC server and gateway server services and then restart the 800xA system
4)Shutdown and restart both the Aspect/Conectivity servers
5)Re-installed the Codesys OPC server on both connectivity server.
With all the above steps, I am still unable to re-establish communication.
While the system was stopped,I tried to use an OPC test client on both the servers.While doing doing this, I did not face any issues with respect to establishing communication with the redundant PLCs.However, when I tried to connect an OPC test client while the system was running, the client would hang while trying to connect. A second instance of WinCodesysOPC start, as the OPCserver and gateway server are already started by 800xaOPC client.
In the inspector tool of the gateway server, the no of tcp/ip data block parameter value increments very slowly or remains constant.generally this count increases whenever the communication with the PLC is good.
Note:Due to lack of time, we are currently doing testing without license installed for FAT,as it will take few more days for abb to supply us with the license file.
Hence, can this issue be because of non installation of license?
Can anybody suggest any more trouble shooting steps?
Also, what exactly is meant by the message, unable to establish connection with connectivity server, when trying to configure the PLCOPCClient version5.0.0-0 client protocol.This message is not persistantly seen every time configuration is being done.
I am able to establish communication on 5.1 Sytem single engineering PC without any issues.
After a very long day of trouble shooting and with the help of regional abb support, the reason for the comunication issue was found to be OPC tags which were no longer present in the symbol file (on account of being deleted in the codesys application), but still connected to control structure objects.
Apparently, the 800xA client was detecting BAD tags and causing the OPC server to stop/ connectivity server to failover. As mentioned earlier, OPC communication was okay for a few days even with the deleted tags still being connected.This made trouble shooting harder, as we did not consider the deleted tags to be an issue initially.
Due to the the communication issue, all tags connected to the objects were being shown as BAD.Hence, it was becoming difficult to identify which OPC tags were suspect.
Later, managed to establish communication via. a single server and identied all the BAD tags. After the suspect tags were either deleted or made unconnected, 800xA OPC driver was reconfigured for redundant OPC communication with controllers and the servers restarted. The Softpoint servers synchronised for a finite duration and came into service mode immediately after the codesys OPC servers established a steady connnection with the redundant PLCs (During the period the issue persisted, it was observed that any one of the redundant Softpoint servers would always remain in Synchronising/Standby state).
This issue sometime re-occurs while downloading a modified program to the redundant CPUs.However, after downloading the same program on both the CPUs and restarting them , the issue resolves.