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Data exchange speed

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07 Jul 2021 10:28 #9926 by lamar
Replied by lamar on topic Data exchange speed
This topic is answered. Thank you.

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07 Jul 2021 10:03 #9917 by support
Replied by support on topic Data exchange speed
Yes, it should be. That's what the design is. If it does not work for you, it needs to be addressed like any other issue, i.e. describe the steps taken, actual behavior, expected behavior (well, we have that one), provide the code, etc.

Regards

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07 Jul 2021 10:00 #9916 by lamar
Replied by lamar on topic Data exchange speed
"Even more, it does not even have to any valid one."

Please check my post:
www.opclabs.com/forum/com-reading-writing-subscriptions-prop...cribing-to-a-non-existent-item

Is it truly safe to subscribe to a non-existent item?

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07 Jul 2021 09:46 #9913 by support
Replied by support on topic Data exchange speed
It would work, by I'd rather suggest to increase the hold periods.

If you want to go your way, you do not have to subscribe to all of those items. One is enough. In fact, it can be ANY item on that server. Even more, it does not even have to any valid one.

Best regards

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07 Jul 2021 08:45 #9910 by lamar
Replied by lamar on topic Data exchange speed
If I write an item less frequently than 5 sec can it be an advisable thing, to subscrube to the written items without handling their events?

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07 Jul 2021 08:40 #9909 by support
Replied by support on topic Data exchange speed
Hello.

The defaults are (in millseconds):
        public const int DefaultItemDetach = 5 * 1000;
        public const int DefaultServerDetach = 10 * 1000;
        public const int DefaultTopicRead = 30 * 1000;
        public const int DefaultTopicWrite = 30 * 1000;
I cannot give you the estimate on "B", because it depends on many factors, but I expect it to be quite significant.

Best regards

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07 Jul 2021 08:10 #9908 by lamar
Replied by lamar on topic Data exchange speed
Okay, I found in the manual, how to set "hold period", but please let me know the default amount of this time.

Another question
when I write 10 tags, could you please estimate the "B" factor in the following relation

time_of ( 10x WriteItemValues ) = B * time_of ( WriteMultipleItemValues [10] )

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07 Jul 2021 08:04 #9907 by lamar
Replied by lamar on topic Data exchange speed
Hi, thank you.
I forgot to subscribe to this topic, so I missed your reply unfortunately.

"if you do not use the server for some, QuickOPC will disconnect"

Could you please specify this time?

Where can I set the may need to increase the "hold period"?

thanks

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28 Jun 2021 12:56 #9832 by support
Replied by support on topic Data exchange speed
Hello,

this is because most of the delay is not the actual data exchange, but a connection setup.
QuickOPC manages the connections (and disconnections) automatically, so you will see the first operation to any OPC server will take longer. Also, if you do not use the server for some, QuickOPC will disconnect and you will see the delay again.

If you are seeing it not just first time, but also later, you may need to increase the "hold period", so that QuickOPC keeps the connection open for longer time.

Any active subscriptions cause the connection be maintained open, until unsubscribed, too.

Best regards

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28 Jun 2021 10:56 - 28 Jun 2021 12:15 #9827 by lamar
Data exchange speed was created by lamar
Hi,

is that normal that the "EasyDAClient.ReadItemValue" and
"EasyDAClient.WriteItemValue" functions are extremely slow?

The first data exchange takes 400-600 ms.

Thanks.
Last edit: 28 Jun 2021 12:15 by lamar.

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