serial modem communications

[chirs73]

I'm trying to develop a test in which labview tells a modem go off hook, dial through an emulator to a test board, and either makes some commands using either *7 or *0 or just connect to a second modem and handshake. Has anyone ever accomplished this and if so, could you just point me in the proper direction for starting this.

Thanks

Chirs73

[RavensFan]

Look at the examples in the example finder for Basic Serial Write and Read.

Search the forums for serial and for modems, I'm sure there are other posts where this has been discussed.

Also make sure you have a good reference for the modem commands.  Such commands as "ATH0" and "ATH1" and "ATDT"

[Raj_V]

Chirs73,

I would recommend checking out this knowledgebase article on how to get started with communicating with a Serial device such as a Modem. 

http://digital.ni.com/public.nsf/allkb/E22DA85E97818DE78625678C0069BFC9?OpenDocument

You might also consider reading through the forum post below as it goes through various stages of getting a working modem communication.

http://forums.ni.com/ni/board/message?board.id=170&message.id=438665&query.id=1928754#M438665

[chirs73]

I've gotten part of the test figured out with a sending numeric page vi. I can't get the modems to handshake with each other. Any advice on this

Thanks

Chirs73

[chirs73]

Here is my code for one modem calling the other modem. The second modem does not pick up and handshake.

[Mark_Yedinak]

What is your hardware configuration? Your program is using both COM1 and COM2. Are you talking to two different modems? Do you want the commands to be sent to the same modem? If you, you are not doing that unless your single modems has two serial ports on it. Also, you assert the DTR line on the first write but never unassert it.

[chirs73]

Here is a drawing of how the whole setup is supposed to be. Modem 1 on COM2 has to call through a TLE to our test PCB and the test PCB will ring Modem 2 on COM1 and then Modem 2 needs to go off hook and handshake with Modem 1 and then disconnect. Then Modem 2 has to be connected to another port on the Test PCB and the same test run again.

[chirs73]

And I also am having trouble setting up the PXI stuff on my development computer due to it will not be attached to my development PC.

Thanks

[Raj_V]

Chirs73,

I'm a little curious about your application. Have you tried breaking up your application into two segments for debugging purposes? Which part of the application are you currently having issues on? Are you able to make modem2 ring through the PCB? If this is not working, can you confirm if you can make the modem2 ring when it's directly connected to the machine using a simple LabVIEW application.

The other side of it would be to simply establish a connection to modem2 directly rather than through the PCB to see if we can get it to go off hook and handshake.

If both of these can be done, then we can  isolate the problem to be going through the PCB and look deeper into it.

[chirs73]

Ok I've gotten the second modem to go off hook and start to handshake but I am not sure if the test is going to fast or what but the modems lock up during the handshake. I have attached the modified version of the program.