No such host is known

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berqo127
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No such host is known

Post by berqo127 »

Hi,

I'm trying to connect to Siemens OPC server and gets "No such host is known".
Also trying connecting from endpoint received from GetEndpoint raised the same error.

Anyone encountered this error?

Best,
Shlomi

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Support Team
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Re: No such host is known

Post by Support Team »

Hi,

can you "ping" the hostname you try to use within the OPC UA Discovery URL?

I seems like your network infrastructure has no proper domain name resolution (DNS) running.
You need to fix this first, before trying to use OPC UA. If not even the basic "ping" is working in your network, how should OPC UA work on that infrastructure?
Best regards
Unified Automation Support Team

berqo127
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Re: No such host is known

Post by berqo127 »

Hi,

The ping works and also using IP address gives the same results.

Please note that using basicClient and clientGetStarted from the SDK examples also raise the same error BUT when using Unified Automation Ua Expert the connection is established.

Thanks,
Shlomi

berqo127
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Re: No such host is known

Post by berqo127 »

-- update it works now --

After getting the DNS resolver run and establishing the connection with the DNS name it works.
I still don't get why connecting directly with the IP address raise "No such host is known".

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Re: No such host is known

Post by Support Team »

Hi,

ping works and address resolution is fine, perfect.

Now we need to look into the Endpoint Description of the UA Server, we must find out what the UA server think is his own hostname.
To check that, connect with UaExpert and open (add document) the "ServerDiagnostic" View, in the first tab "Endpoints" you can see the UA Server response, check DiscoveryURL and EndpointURL and check what "hostname" is used in this description. The expectation is that the hostname returned in Endpoint Description is the real working one, and that it can be used to create the connection.

Is hostname different in DiscoveryURL and EndpointURL, and is it different from the hostname returned by "ping"?
Best regards
Unified Automation Support Team

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