Unacknowledge shared variables (how to)

Hi everybody,
I'm using LabVIEW 8.21 ald its corresponding DSC module in order to perform a standard SCADA system and there's a requirement from my client, taking into account the importance of correcting the alarmed signals, which is the following:
Supposing there's a variable which is out of the range of acceptance (in alarm) and the operator has acknowledged this alarm, if after a certain amount of time (configured by the user) if the reason of the alarm has not been corrected, the corresponding alarm (variable) should change from "acknowledged" to "UNacknowledged" and DSC doesn't have an easy way to perform this. I've tried stopping and restarting its corresponding process and it works fine (the alarm reactivates as an UNacknowledged alarm), but is TOO slow. my question is, is there a better way to perform this operation or I will have to conform myself with this delay?, That is all that LabVIEW DSC is able to do?.
Hope someone can help me
Thanks in advance!
Ignacio

This is how we accomplish this - make sure you keep the blank line
set feedback off termout off verify off line 500 pages 9999 head off pau off
define var myvar
select * from myTable
where id = &var
spool myfile
spool off

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How to use shared variables to address multiple Watlow controllers on the same COM port

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I am trying to use LabVIEW 2010 to control 4 Watlow temperature controllers on one COM port. 3 are Model 96 and 1 is an EZ zone controller. Each controller has a unique modbus address, and I am trying to read from and write to individual registers (such as closed loop setpoint) using shared variables. I am getting return data when reading (although the data appears to be invalid), but am unable to change the value in the register by writing. How can I be sure that the Modbus server is sending commands to the correct controller?
Chuck
Solved!
Go to Solution.

Peter,
Thanks for the reply. I have actually solved that problem. I realized that the Modbus server address has to be the same as the controller's Modbus address.
I have, however, run into another problem. Perhaps you could help me with that. I have a system with 4 Watlow controllers, 3 are series 96 controllers, one is PID only and 2 are ramping. The 4th controller is an EZ zone. I am using RS485 for communications and the controllers are all wired in parallel for communications and power.
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How to add a new Shared Variable programmatically to an existing and deployed library?

Hi there!
I am trying to accomplish this on both LabVIEW 8.6 and LabVIEW 2010 and seems like it's not any different in this situation.
My case: A project has a library with 4 Shared Variables (SVs). The library and the variables are deployed (visible in Distributed System Manager 8.6/2010). I want to add 2 more variables into this library. It is possible to do this manually from Project Explorer window's options menu. But while running an application it has to be done programmatically. Can I provide the library reference to the one currently existing without creating a new one?
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OR
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Vaibhav

<<<<>>>>
As the above two images show, while a library does not exist, it is easy to use the "CreateOrAddLibraryToProject.vi" which will add a new library to the project (if it doesn't exist on file system, a new library will be created) and that way, using the reference (the green wire going out from the function and the Case Structure, can be used to add Shared Variables to the library. The problem was what to do when a library already exists in the project, how to add more variables to it. I was looking for a way to get a library reference, and somehow I could not see it inside a Project's property (VI Server functions). Hence I posted the question. And upon continuing my search, I found it on the Application's property list.
I hope it was useful for someone else as well. And thanks for the replies. Please share a better idea if you have.
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How to read shared variables inside event structure ?

Hi,
I have a problem that my shared variables do not update inside event structure. The program(s) I am trying to get working is seen in the attached screenshot. It works as follows:
0. I start the vi that is unsquared.
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2. I run the other vi (blue square), this changes the boolean shared variable.
The unsquared vi has been running the whole time, it has event structure bind to boolean shared variable change (the one in blue vi). After I have runned the blue vi, the unsquared vi should change the indicator values to match the ones in red vi. However I have to start the blue vi multiple times to get it to change, sometimes even 6 times.
Also, when I change the value in red vi to a third value and start blue vi multiple times, the unsquared vi shows all the variables. I.e. I put "cat" to red then start red, put "mouse" to red then start red,... and then start clicking blue... Unsqured shows cat, mouse,..., dog (dog is the default).
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Attachments:
Screenshot-5.png ‏108 KB

Found the buffering... disabling it solved the problem... thanks.
FYI, there is another solution that I just found out... attached. Adding timeout to the event structure and the variable read outside the event structure... This makes the shared variable strings (one that is read outside and the otherone that is read inside) different.
Could someone explain why the variables are in different state even if they are used in the same place and looped with 10ms intervals?
Juha
Attachments:
Screenshot-6.png ‏110 KB

How do you synchronize accesses to a LabVIEW Shared Variable?

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Wendy,
I am afraid Semaphores are not network-shared objects (to my knowledge), they are system-level objects that use operating-system synchronization mechanisms. If I were synchronizing on a single machine, a semaphore might be a valid mechanism; as an aside, most user-mode semaphores are designed to synchronize within a single process - to synchronize between processes you need to store the semaphore in the Kernel, and to synchronize over a network you would need a network node to handle serialization of requests. My Shared Variable is published over a network, and to my knowledge there are no network-published synchronization mechanisms available - mostly because there is no way to currently perform an atomic test-and-set on the Shared Variable (am I correct?) and there isn't a mechanism for blocking access to a Shared Variable from another network device/machine (or is there?). I've been looking for some way to implement an atomic test-and-set but I am running into a wall; I know that if I select the "single writer" attribute of the Shared Variable I can get LabVIEW to force a single writer allowing me to have an atomic "set", but I need more than that.
If only there was a network-shared Semaphore or some way to block other network accesses to the Shared Variable I would be in business - something like what I want doesn't exist, does it?
Thanks!
-Danny
Message Edited by texasdiaz on 02-23-2006 02:52 AM

I want to work with shared variables. How can I add a remote pc?

I did an aplication to work with shared variables, but I do not know how add a remote pc. I tried make it in Variable Manager, but Labview showed a error message: "Cannot Connect to Target xxxxxxxx". What can I do?

Message Edité par JeromeL le 08-28-2007 06:44 AM
Jérôme LIBBRECHT

How can I get a list of available shared variables from my device?

I have to develop a program to connect to many OPC ready devices. I don't have these devices yet but I have setup two PCs. One is simulating a device. Does anyone know how to read a list of the available shared variables on a device or on another PC so that I can use them later on in the program for reading and writing?
Thanks
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There is a community example that lays out what I think you want to do. You can find it here:
http://decibel.ni.com/content/docs/DOC-9523
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National Instruments
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How to use shared variables with native c programs

Hello
What is the way to use shared variables with native c programs?
I have a c/c++ program that uses the NIDAQmx C-API to perform measurements. Now I want to communicate to a LabVIEW program via shared variables.
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Thanks in Advance

Hi user42,
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http://forums.ni.com/ni/board/message?board.id=180&message.id=24569&requireLogin=False
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http://digital.ni.com/public.nsf/allkb/CC4343488413A2F586256E6200099638?OpenDocument
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How to convert variables on program to shared variables?

Hi I want the controls and indicators of an already existing programs to be available on the Data Dashboard of a tablet/phone. What are the steps to follow if I want to convert them into shared variables so that I can send them to the dashboard. I just found results on how to create new shared variables.
Also the existing program is a state machine. So will the variables be available on the dashboard simulteneously or is it possible to visualise the controls in the form of multiples tabs on Dashboard, like it is on the original program?

I don't know of any way to convert the controls to shared variables. You're going to have to create the shared variables fresh and wire them up in a way that makes sense for your application.
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http://www.ni.com/white-paper/13757/en/

How many clients subscribed to shared variable engine

Hi,
I have shared variable engine deployed on RT and want to know how many clients get access to the shared variables. Is it possible? Thanks!
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So you shouldn't use that much clients or host the SVE at the host computer if possible.
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How Can i retain the Shared Variable Values after PC rebooting

Hi all,
I am facing a paculiar problem with Shared Variables. I have an application in which shared variables are used for data communication.
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As per the my understanding, the variable values will retain eventhough the PC is rebooted. But here i can observe a paculiar problem like some library variables are retaing the values while some others not. I enabled logging for all the variables.
I tried many ways. like logging enabled, logging disabled, changing variable names, changing process names etc... But i am not getting a consistent behaviour.
I hope some you can help me in solving this issue.. "How Can i retain the Shared Variable Values after PC rebooting"
Thanks and Regards,
Mir

Hi Blackperl,
Thanks for the post and I hope your well.
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I beleived the value read back
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engine comes back on-line it will default to this value. Setting a bad
status alarm for the shared variable is also a good way of handling
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I guess, if you could explain to me again that would be great. From my point of view, if I have a cRIO and a Windows PC. If the windows PC crashes, the cRIO will still update its shared variables. Then once the PC has started up its own shared variable engine, and the bindings are loaded, it will once again continue to update its copies of the variables.
Please let me know what you think,
Kind Regards,
James.
Kind Regards
James Hillman
Applications Engineer 2008 to 2009 National Instruments UK & Ireland
Loughborough University UK - 2006 to 2011
Remember Kudos those who help!

How do I install Shared Variable Engine on a computer not having Labview?

Hi,
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Hi
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Thanks
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Attachments:
HMI Test.zip ‏144 KB

How can I change my Shared Variable from "I/O Variable" to "Network Published"

Hello,
I have an application that is using a series of NI wireless sensor nodes. I am trying to programmatically access shared variables. Right now the only method I have found to access the data from the shared variables is datasocket read. I am on labview 8.6.1 so I don't have as many shared variable options as newer versions of labview. I do think there is a way to access properties for the shared variables, but I'm not sure about how to change the nodes channel properties to "Network-Published". Do i need to remove the node from the project and bring it back in with the new settings? When i have done this in the past i have run into naming conflicts. I would appreciate any ligtht that can be shed on this issue that will help me create a vi that operates quicker.

Any Shared Variable that has “I/O Variable” for its Variable Type (see screenshot of the Shared Variable Properties below) refers to any channel of data (such as Analog Input or Output or Digital Input or Output) directly from a module channel. In other words, this is how you directly get the raw reading straight from (or to!) a specific module channel.
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How to update shared variables

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Unacknowledge shared variables (how to)

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