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Value conversion and other [browse issues]

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07 Apr 2017 08:04 #5089 by support
I understand. In your earlier post, however, you have written

That PLC1 that is only available the first time I look for a tag.

After the first time it is nog shown and it gives an error.


Please provide the details of the error.

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07 Apr 2017 08:02 #5088 by support
In the demo application, this behavior is by design, i.e. the value is written when the user presses the corresponding button. A source code of the demo application goes with the product, so if you need it differently, you can have a look at how it is done, and modify it.

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06 Apr 2017 08:41 #5085 by wim.roeloffs2@hotmail.nl
In the example EasyOPCDemo I can write a value but then I need to push the write button and under there us a write action programed.

I hope It makes something clear.

Greatring From Wim Roeloffs This email address is being protected from spambots. You need JavaScript enabled to view it. or This email address is being protected from spambots. You need JavaScript enabled to view it.

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06 Apr 2017 08:29 #5084 by wim.roeloffs2@hotmail.nl
The same think happens when I try one of your demo software the easyOPCDotnetDemo

Sometimes he sees the PLC1 branche and most of the time not.

I do not know why.

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06 Apr 2017 05:16 #5083 by support
Normally, the server should report an error when the write does not succeed, and QuickOPC transforms that error into an exception. It can be a server problem, and if your intuition is telling you that it has to do with data types/conversions, you may even be right; but it's impossible to tell without further analysis.

HOW do you test the Write? Is it e.g. with the Demo application that comes with QuickOPC, or do you have your own code? If you are doing it from code, definitively post it here, otherwise I won't be able to help.

Best regards

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05 Apr 2017 16:44 #5082 by wim.roeloffs2@hotmail.nl
I do not get an exeption but the value does not change in the OPC DA Server from Hitachi

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05 Apr 2017 16:42 #5081 by wim.roeloffs2@hotmail.nl
I can try a picture but i try to explain more.
Under the server name the Name PLC1 apairs but only the first time.
It does not show up the second time. It can be QuickOPC fault or an shortnes of license or It is Hitachies fault. I do not know But if the ItemID is choosen then it stays there.

I hope you can understand me.

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05 Apr 2017 16:38 #5080 by wim.roeloffs2@hotmail.nl
1C A do nog get an exeption but The value does not change in te OPC DA Server

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05 Apr 2017 16:37 #5079 by wim.roeloffs2@hotmail.nl
I do not know for sure if it translate in to a string

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05 Apr 2017 13:24 #5078 by support
I have to admit that I understand you just partially. But I will try to do my best. What's most important, you need to describe precisely what you are seeing.

In your last post, you have written "...and it gives an error.". What was the error saying? Precisely please. You really need to post all possible details about the error here.

Value conversions: OPC servers normally provide values for a particular item using its so-called "canonical data type". So, in a reasonable server, an integer value would also be returned as an integer. In opposite direction (when writing) (at least according to the latest versions of the specs), the server is supposed to make the conversion whenever possible, so even if you write a string, a compliant server should (for an integer item) convert it to integer anyway.

There are ways to specify a concrete data type e.g. when subscribing. And there are way to make conversion yourself in your code (I am assuming you are using C# or .VB.NET - is that true?).

Either way, you need to show me first what precisely you want to achieve, and what you have tried already, and where it does not fulfill what you are looking for.

Best regards

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