Is it possible to remotely control another Labview App via RS-232

[MLDEV]

I need to control another Labview app via RS-232 over a radio modem. The concept is to take an instance of an existing Labview app and move it out to the remote end of a point to point radio modem link and create a look alike panel that will appear to the user to be the same app, at the local control site. The current app just instructs a computer to generate tones and tone packages via its sound card and applies them to an amp. I want to have the local app tell the remote app to execute a button handler when that same button on the local control app is pressed.

I am not a Labview programmer but have developed in other languages for 15 years.

constraints: No Internet/Web available at remote site.

[Pnt]

Your application will send bytes to the RS232 through VISA. You must make a protokol for those bytew so the other application will recognize them.

The other application will read VISA (RS232), and display or do the proper things. It's easy, you will have no problem.

For testing use the two applications in one PC connected through two serial ports of the same PC.

I think you will love Labview... enjoy...

[Matthew_Kelton]

Sure.  You'd have to create a server and client application and define your command protocol.  It's going to require development time and rewrite of the current application.  NI-VISA has the ability to open and close COM ports and transmit and receive data.  There are several shipping examples of serial communication that ship with LabVIEW, and the TCP Server Client examples can be modified for Serial if you have trouble with that.

One word of caution:  Don't assume that because of your other progamming experience that LabVIEW will be a breeze to pick up.

[PhillipBrooks]

Use intermediate VIs to send and receive strings (messages) between the apps.

You say there is no internet connection, but someone will inevitably ask "Can we do this over Ethernet or the internet too?"

If you abstract it and use messages now, you can use add/replace your VISA reads/writes with TCP or UDP reads/writes.

[Ben]

Its been ten years since I did this but it is possible to run TCP/IP over serial if you know how to tinker with and prod Windows to do so.

Once that is done you can use VI server to interact with the remote machine.

Sorry I do not remeber the details.

Ben

PS by today's standards this will appear dog slow.

Message Edited by Ben on 12-14-2007 01:19 PM

[Pnt]

What is the reason for using TCP/IP?

The connection is point to point, and the more simple thing, and the faster, will be just read/write to serial port.

TCP/IP will help only for future upgrades, if internet connection becomes available.

[unclebump]

Could this be done with an opc server??

[PhillipBrooks]

I think Ben might have been referring to using SLIP or PPP. These are implemented at the OS level. You would only need to support one comm protocol in your app.

I would check if the radio modems are SLIP/PPP capable...

[MLDEV]

These radio modem are fairly sophisticated. In any case I have written several GUI  Control panels for legacy command line apps and it appears from the replies here that I can use some of the same teqniques for this. To date everything I had seen addressed doing this via IP and did not mention serial. Thanks for the info.

[Pnt]

As i am not familiar with PPP or SLIP, can you tell me the advantages of using those protocols and not simple serial read-write (with custom simple protocol) ?

If you have a nice link it will be usefull too.

Thanks