USBTMC and the USB488 subclass

[Andy Peters]

Hi, all,

Does NI-VISA's built-in support for USBTMC devices require such devices to declare and use the USB488 subclass, as "suggested" in the USBTMC specification (.zip)?

thanks,
-a

[Ebele_Obijiofor]

Hi a,

NI-VISA supports both USBTMC and USB488 devices, and does not require a device to use the USB488 specification. The device MUST however conform fully to the ENTIRE USBTMC specifications in order to work with NI-VISA. Hope this helps.

Thanks!

Message Edited by _Belle on 03-09-2006 12:35 PM

[GPIB_Guru]

What kind of device are you making? National Instruments offers NI-Device, which handles the USBTMC-USB488 standard automatically for you. It has certain OS and hardware requirements, but it may be something to consider if you are starting a new project and have choices.

[Andy Peters]

Type of device?  A logic analyzer.  The hardware is a pod with ports that connect to a DUT, and the host computer provides the user interface.  USB provides the connection between the host and the pod.  LabView's Digital Waveform Graph control is convenient for the waveform display.

I haven't decided what class I'll use for the device, as I want to avoid writing a driver.  One option I'm considering is to use HID for the various controls and a bulk IN endpoint for the data, using LibUSB for the bulk interface.  The other idea is to use the USB TMC.  I suppose the question here is since there's no standard driver provided by the OS, I'll still have to provide such a driver, since I would assume that LabView talks to driver?

-a

[Makoto]

I highly recommend you to adopt USBTMC-USB488 class, because it is natural to categorize your logic analyzer to T&M instruments.  If you and/or your customers want to remote control the instrument using LabVIEW, NI-VISA that natively supports USBTMC and USBTMC-USB488 instruments can be used very easily.   

Also, if you plan to implement IEEE488.2/SCPI or similar ASCII command-based programming interface on your instrument, the USBTMC-USB488 class is the best choice as the class specifications are well considered for designing GPIB-like command interfaces.  Even if using USBTMC-USB488, however, your instrument does not have to be IEEE488.2/SCPI compliant. 

このメッセージは　03-23-2006 10:39 AMに Makoto が編集しています。