The difference between NI MAX and Agilent VISA ??

[Albert Sung]

Dear sirs,

I am developing the USBTMC device to interface with VISA application on PC.

When I try to communicate with the Agilent VISA (Agilent Connection Expert), it can detect and control my device.

But when I try to communicate with the NI VISA (NI MAX), it can not detect my device.

I want to know if both VISA applications have some difference about detection or verification process ?!

Why can't my USBTMC device communicate with both applications ?!

(I have tried the Agilent driver "ausbtmc.sys" and NI driver "niusbtmc.sys".)

Has anyone used the Agilent VISA ?!

Please help me !!

Thanks a lot !!

Albert Sung

[Makoto]

> Has anyone used the Agilent VISA ?!

Yes I often use NI VISA and Agilent VISA (IO Libraries Suite 14.x) both are well working with USBTMC instruments.  However I do not recommend to install both VISA software on the same PC at the same time.  Unexpected conflict can raise.  To switch the VISA library to other vendor's type, uninstall the existing VISA completely (also make sure to clean up VISA32.DLL from System32 directory), then reinstall the other VISA.

The VISA library's USBTMC DLL layer communicates with lower USBTMC kernel-mode driver, but the "bridge" architecture between the DLL and kernel-mode driver is different depending on VISA vendor.  (This bridging architecture is not unified by VISA spec nor USBTMC spec.)  Therefore, just re-installing other VISA is not enough.  Your USBTMC device must change its hosting driver by hand at Control Panel -> Device Manager.  (The device-to-driver mapping information is stored in System Registry but its mapping status keeps undeleted even if the VISA library has been uninstalled, therefore it must be managed by hands.)

このメッセージは　02-08-2007 10:14 AMに Makoto が編集しています。