DDE Server in Labview

[Tom_P]

I have been trying to operate Labview as a DDE server so that another application can conneect to it.

(1) I don't understand how you access data that is provided to Labview by the client

(2) Is the data that is set in the set block the data that is accessed by using the topic string?

I have been through the examples and documentation and i didnt find an answer for question 1. With question 2 i am just looking for confirmation on how the client accesses the data because i havent actually got it to work yet. DDE is the only method that i am aware of with the program that i am using as the client.

Thanks,

Tom

[Megan B.]

Hi Tom,

Have you come across this tutorial on using DDE in LabVIEW: http://zone.ni.com/devzone/conceptd.nsf/webmain/14134d7ce042edbf86256a3a006bd87c#2?  It has some great information on DDE and even some pictures of example code.  For example, one section shows the use of the DDE Request VI to get information from clients when LabVIEW is your DDE server.  As for your second question, if I'm understanding you properly, you are correct that DDE Set VI writes to the Topic specified in the DDE server VI.

Good luck!
Megan B.
National Instruments

[mikeporter]

Quick question, given the number of other (better) protocols available, why are you lloking at DDE?

Mike...

[Tom_P]

Hi Megan,

I have looked at that link and i am not sure where the use of DDE request in a Server is actually explained. The figures relating to the use of DDE Request all state that the server must be running prior to the use of the VI. If my interpretation is wrong please let me know. Any additional information about the use of DDE Request would be appreciated.

Thanks

Tom

[Tom_P]

Hi Mike,

There are a couple of reasons why i am using DDE. Firstly i have to use something and the program which i want as my client has a DDE block. If it works i don't really care how good the solution is because that is not important to my project. Lastly, i know little about the other options and i am trying to minimise how much time i spend on this problem. If you think there are better, simpler options then i am happy for you to tell me about them.

Thanks,

Tom

[mikeporter]

What's the other program you're communicating with?

Mike...

[Tom_P]

ProcessACT, also known as UNAC.

Tom

[mikeporter]

I did a little poking around on the ProcessACT website and, while the information was sparse, I did find a couple comments that the package supports OPC. That would be a major step up from DDE.

Mike...

[Megan B.]

Hi Tom,

Here is some example code that shows how to use DDE to read and write to an Excel spreadsheet.  Perhaps it will give you a good starting point.  Also, as Mike said, if you can use OPC you may want to consider it.

Good luck!
Megan B.
National Instruments

[Tom_P]

Thanks for the help guys, i'm pretty sure i can sort something out.

Tom