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QuickOPC Standard
unfortunately it is still not clear.
If you wanted something similar to Live Binding, but "non-visual", the answer is negative.
For getting a continuous stream of tag value updates at fastest possible rate, it is suggested that you use subscriptions:
opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...o%20OPC%20Classic%20Items.html
Best regards
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I was meaning the OPCLabs demo scripts showed how to allocate a textbox directly to the OPCtag using the bindings without any code used.
Can the bindings also be allocated directly to a tag within the VB script if I was to read the OPC value on a timer at 100ms - or faster?
hopefully this explains better.
Leslie
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I do not quite understand the question - please try to elaborate more.
Thank you
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I had a look at the bindings option but I will be using the VS to pass the OPC received data onto another application so nothing will actually be shown on VB.
The bindings allocated to the textbox was very quick to implement and I was pleasantly surprised how easy it was to setup.
Can the bindings feature be allocated directly to a tag in VB?
Leslie
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I am glad that it works now.
First, some technical notes.
- The reason you got the issue is a combination of the fact that the "read" calls have a parameter that specifies the maximum value age, and it defaults to 1 second. And, QuickOPC creates subscriptions internally to satisfy repeated reads. The "1 second" thing means that the software tries to get you any value that is newer than that, so it can mix them too. Specifying reads from device is equivalent to setting this parameter to zero, which resolves the issue.
- Repeated reads are a discouraged pattern in OPC. I have not made the comment originally because I understand you wanted to resolve the issue with the way your program is written. However, OPC subscriptions should be used whenever possible. We have examples for this too - in fact, the "HmiScreen" example in the product is quite close.
Regarding the product editions (opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...e.html#Product%20Editions.html ):
- For what you described, QuickOPC Standard is sufficient.
- But, you may want to have a look of what Live Binding feature is. It allows you to simply use Visual Studio designer to bind OPC tags to the controls on the form. No manual coding necessary. If you decide to use that, you would need QuickOPC Professional.
More info to Live Binding:
- opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...%20using%20Live%20Binding.html
- opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...e.html#Live_Binding_Model.html
Best regards
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Many thanks for the help, I can confirm I can now read the tags without the original value overwriting the read values.
Can you advise please, the license I will require to use the EasyDAClient1 interface in visual studio?
looking at the full price list, I see QuickOPCUltimate, QuickOPCProfessional, and QuickOPCStandard.
kind regards
Leslie
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Can you please change the "read" statements similarly to the following?:
TextBox2.Text = EasyDAClient1.ReadItemValue("Kepware.KEPServerEX.V6", "Channel1.TestPLC.TestAngle", DADataSource.Device)Thank you
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I have also taken another movie with the kepware OPC client to show the values being sent from the Server.
You can see that the values are being read but somehow over written by itself?
Hopefully this shows more useful info.
Leslie
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Sorry, never pressed the insert button earlier
!
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please attach the video (beware of the user interface in Forums which requires you to Add the file and then also Insert it).
Best regards
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