Keep alive request fail|OPC UA Implementation: Stacks, Tools, and Samples|Forum|OPC Foundation

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Keep alive request fail
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Gurcan Bicer
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06/12/2018
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11/04/2019 - 23:00
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Hi, I have a problem with OPC UA connection that I cannot resolve it.

The client application is running on the same server as OPC server (kepware).

 

Parameters are;

for session;

KeepAlive = 1000 , Lifetimecount = 5000

for subscriptions;

subscription = new Subscription()
{
PublishingInterval = 50,
PublishingEnabled = true,
KeepAliveCount = 1000,
LifetimeCount = 5000,
MaxNotificationsPerPublish = 0,
DisplayName = m_ConnectionType.ToString(),
MaxMessageCount = int.MaxValue,
MinLifetimeInterval = 1000,
DisableMonitoredItemCache = false,
TimestampsToReturn = TimestampsToReturn.Both,
FastDataChangeCallback = new FastDataChangeNotificationEventHandler(fastChange)
};

 

The error happens at "keep alive requests";

BadNoCommunication 'Server not responding to keep alive requests.'

 

I cannot reproduce this issue, it happens now and then.. there is no issue on reconnection, it works.. but I lose data during reconnection process.

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Randy Armstrong
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05/30/2017
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11/05/2019 - 07:54
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The keepalive in this cases likely refers to a watchdog which calls Read on ServerStatus.

This can fail if the network connection is unreliable or if the server is slow processing requests.

There should be a timeout on the session object that controls the frequency but you need to understand why a simple read would be delayed.

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