Troubling communicating with hp34401A using RS-232

[Pondered]

I am trying to contol a HP34401A (multimeter) by RS-232.  I check the settings on the Com1 port, the settings on the multimeter, and the settings on the front panel interface and the all match up.  There is a section on the HP34401A Initialize.VI that asks for the Instrument Descriptor, but I don't know what to put there.   I am using address 4.  Whenever I run the vi, I get error:  

Error -1073807195 occurred at Old VISA Open in HP34401A Initialize.vi.

Possible reasons:

VISA:  (Hex 0xBFFF00A5) The interface type is valid but the specified interface number is not configured.

What can I do I solve this problem?

[Pondered]

I tried looking in context help and under Instrument Descriptor I put ASRL[COM1]::INSTR, but now for an error I get:

Error -1073807343 occurred at Old VISA Open in HP34401A Initialize.vi.

Possible reasons:

VISA:  (Hex 0xBFFF0011) Insufficient location information or the device or resource is not present in the system.

What could the problem be?

[Pondered]

I changed my Instrument Descriptor to ASRL1::INSTR and the first error is gone, but now I get

Error -1073807331 occurred at Property Node (arg 9) in HP34401A Initialize.vi.

Possible reasons:

VISA:  (Hex 0xBFFF001D) The specified attribute is not defined or supported by the referenced resource.

What could be the reasons?

[Pondered]

I also get error:

Error -1073807339 occurred at VISA Read in HP34401A Control Mode.vi.

Possible reasons:

VISA:  (Hex 0xBFFF0015) Timeout expired before operation completed.

[Dennis_Knutson]

What version of LabVIEW and VISA are you running and which version of the 34401 driver did you download? The 'Old VISA Open' isn't in any of the the drivers on NI's site. The drivers for 6.0 and 7.0 only have 7 arguments for the property node in the initialize function. The front panel of all VIs in the driver should have a VISA Resource Name control that you can simply click on the little arrow on the right side to view all available VISA resource and select the one you need. If you are using LabVIEW 6 or later, you should download a current driver and make sure your version of VISA is current. Also, before you run anything in LabVIEW, you should check communication to the instrument in either MAX or Hyperterminal. This will verify the serial settings (baud rate, parity, etc.) and that you have the correct type of serial cable.

[Pondered]

I am still having trouble with the HP34401A.  When I try to use MAX to try to test the device, it is not letting me communicate with it.  I checked to make sure that all of the settings matched up.  I don't know what else to do.

[Pondered]

I am also getting this error when ever I try to initialize the device:

Error -1073807339 occurred at VISA Read in HP34401A Control Mode.vi

Possible reason(s):

VISA:  (Hex 0xBFFF0015) Timeout expired before operation completed.

What can I do to fix this problem?

[Dennis_Knutson]

What do you mean that MAX will not 'let' you communicate with it? When you select a com port in MAX, you just right click and select Open VISA Session. You go to the Basic I/O tab and select either Write or Read. Be sure to include a termination character in your write string. If you get an error there, then that's a little different. I think the first step in trying to setup a serial instrument is to use something like Hyperterminal or Procomm. Hperterminal comes with windows and is easy to use. Hyperterminal automatically adds CR and LF characters so you don't have to worry about that. Just getting a response after sending a *IDN? will confirm that the com port parameters are set correctly and you have the right cable. Are you using a null modem cable?

[MJF]

If he is using a null modem cable, that is the wrong type to use with that instrument. He needs a standard RS-232 cable.

[Pondered]

After I try to communicate with the device through MAX, it gives me this error whenever I try to read from it:

BFFF0015

VI_ERROR_TMO                

Timeout expired before operation completed.

I am not able to write to it, b/c  don't know any commands.    I checked the settings and they all match up. I am not sure what type of modem I am using.  I am not familar with HyperTerminal.  How would I use that to see if I can communicate with the multimeter?  Is there something else that I can do besides HyperTerminal?  If all else fails, could there be a problem with my RS-232 Link?