Error BadNoCommunication 'Server not responding to keep alive requests.'

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RobFra
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Error BadNoCommunication 'Server not responding to keep alive requests.'

Post by RobFra »

Hi,

we have a client daemon who constantly (1 sec) monitors some tags (just 3 tags) on a OPC UA Server.

The problem is that often (5 to 10 times in 15 hours) it gives BadNoCommunication 'Server not responding to keep alive requests.'

The customers says that he had verified the ethernet adapter, the cable, there are no switchs in between but it is still giving the error.

What does it mean and what can we check more?

Thanks



Rob

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Re: Error BadNoCommunication 'Server not responding to keep alive requests.'

Post by Support Team »

Hi,

the best way for analysing would be a Wireshark recording in combination with a trace-log-file from the two applications.

However the Wireshark is only readable when communication is not encrypted. Specially PC-based UA servers mostly have server-side trace or log file for analytics. On PLC-based UA servers this option may not exist (not enough space). If so, your only option is client-side tracing and log-files. In any case it would make your life easier, when recorded traces and Wireshark capture have sychronized clock.

Secondly you could try to collect information on how "regular" this error occurs, is it all 75 minutes, or is it more "sporadic"? This may give you a hint when correlating with other actions that may occur in the system (e.g. load and overload in the UA server). More guessing than analysing, but may guide you in a direction.

Third option is to use different client (e.g. UaExpert) and connect in parallel (monitor 3 tags in DA-View). Does the Reference-Client experience the same errors? This will give you at least some direction, either for server-side or client-side implementation error (after you have excluded physical network and cabeling issues already).
Best regards
Unified Automation Support Team

RobFra
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Re: Error BadNoCommunication 'Server not responding to keep alive requests.'

Post by RobFra »

Thanks for your suggestions. we will try the 3rd one.
As additional information, we've seen the OPC UA Server log and when the client tacks the BadNoCommunication, the server log says:

"Client logged out of OPC UA Server''
"client logged in into OPC UA Server"

The opc ua server has user and password to authenticate.
Sometimes there is a warning in the opc ua server log that says: warning. Licensing violation.

Can al this information add some clue?

Thanks

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Re: Error BadNoCommunication 'Server not responding to keep alive requests.'

Post by Support Team »

Hi,

who is manufacturer of the UA Server? Where did your customer get the server from?

Typically you can read out this information by looking into UA server's adress space:
Root->Objects->Server->ServerStatus->BuildInfo-> ???

If you experience same communication error with UaExpert-Client, it is very likely that UA server just stops working (BadNoCommunication). Thereafter the Client typically goes into some automatic "re-connection" loop and creates new connection (hence must login again) whenever UA server comes back to live.

Without knowing the manufacturer of the server, the educated guess is, that (without having a license for it) the server just suddely stops the communication hoping for payment/purchase?
Best regards
Unified Automation Support Team

RobFra
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Re: Error BadNoCommunication 'Server not responding to keep alive requests.'

Post by RobFra »

Thanks for replay.

The machine's manufacturer told me that:

on the PLC the CPU is inside a Power Panel of B&R: 5PPC3100_KBU0_000.
OPC-UA Server is the standard provided by B&R .

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Re: Error BadNoCommunication 'Server not responding to keep alive requests.'

Post by Support Team »

Hi,

you probably need to contact B&R to figure this one out.

The client side should be easily connected over hours and years without any interruption. Keep in mind that client side implementation may check security credentials (secure channel renew). The frequency of the error occurrence (90min to 3hours) somewhat reminds me to the "evaluation period" of serveral software deliverables. But again, this is just a guess.
Best regards
Unified Automation Support Team

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