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Write Not Completed error when writing with the OPC Web Client.

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05 Mar 2015 13:08 #2930 by support
As I wrote earlier, we have made a fix for a problem that could sometimes cause this error on our side. If you download the current build of QuickOPC 5.32 from our download area, it'll have the fix in it already.

The fix was for a problem which would, however, manifest itself as permanent: Once you got "write not completed" for a server, you will always get it for any Write (except when switching to a new EasyDAClient object with Isolated = true setting).

If you are seeing these problems *and they are transient*, i.e. at some later point in time the things return to normal, most likely it is simply the server that takes too long to make the Write. If you would like to verify this, it should be possible to deploy an OPC Analyzer (which acts as middle piece between the client and the server), and capture the communication traces. Do you want to go this route?

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05 Mar 2015 10:59 #2926 by giles
Just bumping this in case you have any other ideas....

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10 Feb 2015 10:08 #2752 by support
That's easy - e.g. like his:
            var client = new EasyDAClient();
            client.InstanceParameters.Timeouts.ReadItem = 5*60*1000;
            client.InstanceParameters.Timeouts.WriteItem = 5*60*1000;

The timeout values are in milliseconds; in the example above, they are thus equal to 5 minutes.

Best regards

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09 Feb 2015 21:54 #2749 by giles
how can i increase the timeout?

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09 Feb 2015 20:47 #2748 by admin
Thank you.

If the retries do help, most likely the error (which is basically a timeout) simply reflects the fact that the server takes such a long time to perform the write. It could even be that the write succeeds the first time already (and the retries are thus not necessary), except that - because we have a preset timeout - you get the error before the write completes. If this is the case, increasing the timeout will resolve the error, and you would be able to remove the retries as well.

Best regards

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09 Feb 2015 10:11 #2745 by giles
1 yes - but I don't seem to get the correspo9nding read error

2 My software is doing up to 10 retries - it works (not sure if it ever even do0es it twice in a row)

3 I will do my best to create a project to send you - just v busy. It's part of a web application so will be interesting to see if i8t still happens with a simple console app.

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09 Feb 2015 07:02 #2742 by support
1. Are you getting the same error message? ("Write not completed...")
2. When it happens, do all "writes" from that moment on return the error, or does it - after some time - start working again?
3. How easily can you reproduce it?

Thank you

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08 Feb 2015 23:08 #2740 by giles
Hi Thanks for this. However I still seem to have the problem - it appears to be only on writes now and I *think* just writing multiple alues.

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05 Feb 2015 11:21 #2714 by support
We have today posted a new build of QuickOPC that addresses the "read/write not completed" errors (in some cases, it was caused by an internal deadlock that is now fixed). The fix is in QuickOPC 5.32.1063.1 (and later). Please download from www.opclabs.com/products/quickopc/downloads , and rebuild your app with the new assemblies. It may help.

Best regards

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03 Feb 2015 11:56 #2677 by giles
Hi thanks - I was writing from hotel and hadn't examined read errors I think the read error is generally this. www.opclabs.com/forum/connections-reconnections-com-dcom/146...d-cannot-connect-topic-timeout

but will find out more ...

A read failure isn't so bad but a write failure where I can't be sure if it succeeeded or not is not good at all as I might do a download twice. I am currently giving it all a really good soak test so will discover more.

Because of my other issue (see my recent post below) I have set holdperiods for topicread, topicwrite and itemdetach to zero - to see if disabling your caching of topics makes a difference. Presumably the reads are then connecting each time.

Sorry to mix up two errors in the same post - the write error is much more concerning I can cope with reads occassionally failing.

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