Help with RS232 Communication without using VISA

[Robber_Tom]

I'm a newcomer to LabVIEW, and am currently trying to interface with an instrument that communicates via an RS232 serial port.  This instrument is not compatible with the VISA tool, and since that (and the DAQ Assistant) is all I've used to interface with instruments, I'm at a loss as to where to head next.  I know the baud rate, data format, stop bit and parity bit, and am able to generate the ASCII commands that I want to send to the instrument; I just need a bit of help on knowing which function I can use to go the rest of the way.  Thanks for any help.

[RavensFan]

Why is the "instrument is not compatible with the VISA tool"?

VISA is a device driver interface that allows LabVIEW and other NI programs to communicate with the serial port on the PC.  It doesn't care about what instrument is on the other end of that serial connection.  Likewise, the instrument on the other end should have no idea whether it is being communicated to it by way of VISA, or any other device driver.

If you are having problems, then it is probably in the way you are using VISA and not within VISA itself.  There may be some other ways that you could have your LabVIEW program access your PC's serial ports without VISA, but you are going to have more headaches and problems that way.

Please provide more details on the problems you are having with using VISA.

[Robber_Tom]

OK, I guess I misunderstood the problem then.  When I was trying to use the VISA I had no way to get a VISA resource name.  When looking at the detailed help, I see I should use ASRL[board]::INSTR but I don't have a board that's hooked up to this.  I was under the impression that I needed a NI board, which I don't have, I just have the serial port of the instrument hooked up to the computer.  I guess then I just don't understand how to determine what to use in the "VISA resource name" input.  Is there a name/number for the serial port on my computer?  Or is that configured another way?

[Omar_II]

Drop a VISA Ref control and select the com port you wish to use if you have com ports installed on your machine.

[RavensFan]

What do you see if you click on the down arrow in the VISA resource?  What if you hit Refresh?

If you have a Com1 in your PC, you should see COM1 show up in the list.

What version of LV do you have installed?  What version of Measurment and Automation Explorer (MAX)?  VISA?

If you look under My System >> Devices and Interfaces >> Serial & Parallel in MAX, what do you see?  You should see the same things that show up in the VISA control if you click on the down arrow.  MAX will also let you rename those ports to a different name if you need to.  There are a lot of posts in the forum that discuss the "ASRL" name format, but I've never seen anything listed that way myself in real life.