Matt, Thank you for your answer I did all you mentioned but unsuccessfully. It's really weird, since even the test from NI called loopback.vi doesn't work. I did further test with windows hyperterminal and with a program I did through VisualBasic, no problem.
As a matter of fact, the purpose of these tests are to widen my knowledge on NI and I recently follow an introduction course on LabView So, I'll ask the application engineer who gave this course about my problem. Thanks again Gérard -- Gérard Férini Switzerland http://home.tiscalinet.ch/gferini "AggieMatt" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] Hi Gérard, Have you checked www.ni.com/idnet to make sure NI doesn't already have a driver for your voltmeter? On the block diagram of loopback.vi, there should be serial port init.vi (or something similar). You may need to configure the baud rate, data bits, stop bits, flow control, etc. different than the default values. You can also set these attributes in Measurement & Automation Explorer. These settings MUST match those on your RS-232 enabled instrument. Lastly, you may want to look at the LV Instrument Driver Templates which include a good shell for communication with RS-232 devices. Available Here: http://www.ni.com/devzone/idnet/development.htm Regards, Matt
