Register for shared variable data value change notifications

[george seifert]

The FAQ on shared variables (#30) says that the "DSC Module adds the ability to register for shared variable alarm and event notifications and data value change notifications as separate event cases in the LabVIEW event structure". I tried to do that, but can't figure out how to register the event. Can anyone clue me in please?

George

[REM1]

The FAQ on shared variables (#30) says that the "DSC Module adds the ability to register for shared variable alarm and event notifications and data value change notifications as separate event cases in the LabVIEW event structure". I tried to do that, but can't figure out how to register the event. Can anyone clue me in please?

George

DSC includes an example for using this feature. Go to the examples directory/lvdsc/Event Structure Support. This should do a pretty good job getting you started.

[george seifert]

DSC includes an example for using this feature. Go to the examples directory/lvdsc/Event Structure Support. This should do a pretty good job getting you started.

Hmm, I don't have a lvdcs subdir in the Examples dir. Is the DSC module a special addon?

George

[Yair]

Hmm, I don't have a lvdcs subdir in the Examples dir. Is the DSC module a special addon?

George

There's nothing special about it. NI would be happy to give it to anyone who would give them money for it.

[REM1]

There's nothing special about it. NI would be happy to give it to anyone who would give them money for it.

While I would argue that there IS something special about it...it is a purchasable add-on and is required to make use of the feature you are asking about.

[Yair]

That's the problem with humor, you never know who you're going to insult.

Anyway, not having used most features of the DSC module (except for mainly the image navigator and the IA OPC server) I'm not one to pass (or not pass) judgement on it.

[REM1]

That's the problem with humor, you never know who you're going to insult.

Anyway, not having used most features of the DSC module (except for mainly the image navigator and the IA OPC server) I'm not one to pass (or not pass) judgement on it.

I wasn't offended...I just forgot to add the smiley to my post.

[MatthewHarrison]

Well, I guess a related question would then be, "Is there any way to register for these shared variable value change events without the entire DSC module installed?" I don't mean to circumvent the need for the DSC which, I'm sure, is well worth it. It just seems that if that is all you want to do, there may be some other way.

-Matt

[REM1]

Well, I guess a related question would then be, "Is there any way to register for these shared variable value change events without the entire DSC module installed?" I don't mean to circumvent the need for the DSC which, I'm sure, is well worth it. It just seems that if that is all you want to do, there may be some other way.

-Matt

Not at this time. DSC had to do a good bit of extra work to get this to work.

[Jordan Kuehn]

I know this thread is a bit old, but relevant to my question.  I'm essentially asking the same question that MatthewHarrison asked at the end regarding shared variable events without the DSC module.  One twist, I've once made this work via bound front panel controls and registering for a value change event of that control.  This was in LV2014.  Now I'm looking to do it again with another customer that doesn't want to pay for DSC and it's not working in LV2015SP1.  Does anyone have any input on getting this to work in either environment?

Edited May 5, 2016 by Jordan Kuehn

[viSci]

Amazing NI is still trying so hard to sell the DSC.  From what I can tell NSV events are possible in CVI without the DSC.  Here is an old thread that ends in some CVI code that show how to register NSV change callbacks.  Now all you have to figure out it how to trigger LV user events from CVI, which I believe is possible.

http://forums.ni.com/t5/LabWindows-CVI/NSV-Async-Read-Callbacks/td-p/1329994

[viSci]

More info on the subject...

http://zone.ni.com/reference/en-XX/help/370051P-01/cvi/libref/cvicnvcreatesubscriber/

[ShaunR]

36 minutes ago, viSci said:

Now all you have to figure out it how to trigger LV user events from CVI,

The same way you do from any DLL -  PostLVUserEvent. Generating events for LabVIEW is trivial. Maintaining a DLL (especially multi-platform)  is a right royal pain in the proverbial,however. 

[Jordan Kuehn]

45 minutes ago, viSci said:

Amazing NI is still trying so hard to sell the DSC.  From what I can tell NSV events are possible in CVI without the DSC.  Here is an old thread that ends in some CVI code that show how to register NSV change callbacks.  Now all you have to figure out it how to trigger LV user events from CVI, which I believe is possible.

http://forums.ni.com/t5/LabWindows-CVI/NSV-Async-Read-Callbacks/td-p/1329994

Agreed, DSC should stand on its own for customers that need a SCADA system.  I would be willing to bet the vast majority of people using NSV Events have no need for anything else in the DSC Module.  At the very least give us a runtime that is free and only has the NSV Events.  

Thanks for the links!  That looks like it would work, but requires a significant investment in time as well as using CVI...

[ShaunR]

13 minutes ago, Jordan Kuehn said:

Agreed, DSC should stand on its own for customers that need a SCADA system.

It did. It was called "BridgeVIEW". They didn't sell many so decided to make it a toolkit instead .

Edited May 6, 2016 by ShaunR

[Jordan Kuehn]

14 minutes ago, ShaunR said:

It did. It was called "BridgeVIEW". They didn't sell many so decided to make it a toolkit instead .

Nice.  1996...

[smithd]

Ah but how much has scada changed since 1996? Everything is still basically just modbus with valve icons, right?