Prob. with HP 34401A for RS-232 communication

[marc france]

Hello everyone,

I am using Labview 7.1 and my O.S is Windows XP.  I am trying to use the Hp 34401A multimeter with Labview. I have used the " HP 34401A single read example " from NI web site and the HP34401A app. available in Labview 7.1. It works fine through GPIB communication. However, when I scroll down the Visa Resource Name and choose " Com1" which I have cheked out to be the right one, it doesn't work. Both ends of the serial cord are correctly connected. I get this message :

"VISA Write dans HP34401A Control Mode.vi->HP34401A Initialize.vi->HP34401A Single Read Example.vi"  

with the error number : -1073807339

I have download and installed NI-VISA Version 3.3.1 for Windows 2000/NT/XP--Includes support for LabVIEW RT and RTX
and VISA Run-time Engine Version 3.4.1 for Windows 2000/XP x64/XP

But this doesn't change anything to the problem.

I have seen on the forum that other people have had a similar problem but I haven't been able to find the correct solution.

Would anybody have an idea what else I could try? Or have a very, very, simple VI that I could try out to see if I succeed in communicating with the Hp instrument through  RS-232.

Any help would be great,

Thanks a lot,

Regards,

Marc

[AndrewAlford]

When I use the Serial port for communication to instruments the VISA Alias I use for COM1 is ASRL1::INSTR. Use Measurement and Automation explorer to verify the instrument is recognized on the Serial Port.

[Dennis_Knutson]

The easiest way to verify communication is with Hyperterminal. Configure a session like the one in LabVIEW (baud rate, parity, etc.) and see if it works when you send an "*IDN?" command.

[marc france]

Hi,

Thank you very much to both of you for your help.

Before I try to communicate through MAX ( or Labview), do I need to install any software related to Hp 34401A so that it is recognized ?

regards,

Marc

[Dennis_Knutson]

Not for the serial port. Unlike the GPIB, MAX cannot detect instruments connected to serial ports - it doesn't even try because there is no such thing as a standard protocol for serial instruments. All MAX will do is detect the serial port itself. You can use MAX to open a VISA session (right click on the com port) and use that instead of Hyperterminal.  It's your choice.

[AndrewAlford]

Not that I know of.