USB device use with VISA

[e-dutisseuil]

Hi all,

I try to make a first communication with any USB device, but I can't even open a VISA session.

For example with a USB-to-RS232 converter device whose informations are:

Device Descriptor:

bcdUSB: 0x0200

idVendor: 0x3923 (National Instruments)

idProduct: 0x7011

bcdDevice: 0x0100

iManufacturer: 0x01

0x0409: "National Instruments"

iProduct: 0x02

0x0409: "USB-232/4 Ports 1 and 2"

iSerialNumber: 0x03

0x0409: "00DA0399"

I try to open the VISA session with different descriptions like:

USB::0x3923::0x7011::0x03::INSTR

USB::0x3923::0x7011::USB-232/4 Ports 1 and 2::INSTR

...

But I always get an error message.

Does anybody see the bugg ???

Thanks for your help

[todd]

If I recall correctly, VISA _only_ includes access to USB devices from the Test and Measurement Class, sub-class USB488 (USBTMC-USB488). A USB to RS232 converter is not a USBTMC device.

[e-dutisseuil]

Thanks Todd

Indeed, every USB devices I tried (USB to RS232 converter, USB key and USB-to-FIFO device) should not be considered as INSTR (or Test and measurement) class but as RAW. The explaination between both given by NI was not very clear to me but your answer help me to find my way. Thanks again.

Now I have to find how to send with LabView a 8bits-data word in my USB-to-FIFO component.

java script:emoticon(':headbang:')

java script:emoticon(':headbang:')

If I recall correctly, VISA _only_ includes access to USB devices from the Test and Measurement Class, sub-class USB488 (USBTMC-USB488). A USB to RS232 converter is not a USBTMC device.

4330[/snapback]

[Jack Kelledes]

Thanks Todd

Indeed, every USB devices I tried (USB to RS232 converter, USB key and USB-to-FIFO device) should not be considered as INSTR (or Test and measurement) class but as RAW. The explaination between both given by NI was not very clear to me but your answer help me to find my way. Thanks again.

Now I have to find how to send with LabView a 8bits-data word in my USB-to-FIFO component. 

java script:emoticon(':headbang:')

java script:emoticon(':headbang:')

4339[/snapback]

My main development computer right now is a laptop and I use a few USB converters.

I don't know about the USB to FIFO device but my USB to RS-232 converter communicates through VISA by accessing the COM port like usual with ASRL4::INSTR.

My USB to GPIB converter also works just like a normal GPIB interface using VISA using GPIB::9::INSTR.

My USB printer also prints through LabVIEW. It's set up as the default on my computer so I think some of that might be handled by Windows.

Basically I don't do anything different using those devices than the ports and cards in my desktop. I don't use any special USB translators or anything else, just the drivers that came with them and installed in Windows. All my VI's are usable on both platforms with no changes.

I've not used a USB key through LabVIEW yet but my computer sees it as an additional drive so I think that LabVIEW would work with it as long as the drive letter is correct. I do know that my USB key is really slow so I probably wouldn't use it for my primary data storage.

Hope this helps.

Jack

[rkerns]

What operating system are you using? We previously used Sewell Direct's USB232 dongle, but when we upgraded to OSx 10.3.5 it stopped functioning and would give error messages.

It turns out the prolific PL2303 chipset used in the dongle was no longer support by the Mac, so we switched to a keyspan USB232 and our problems went away

When using VISAfind.vi a USB232 is generally will show up as ASRL2::INSTR or similar.

[Jack Kelledes]

I currently use Windows XP on my laptop but also have one OSx desktop computer that I've used it on.

I have found that there is some difference in compatibility with the USB to RS-232 converters. I have gone through 3 or 4 of them just trying to find one that works on each machine I need it on. I finally got a cheap Targus model just for kicks and it's worked the best for me.

My biggest problem when using USB converters is the power they consume. I have a 4 port USB hub (with its own power supply) with most things plugged into it and sometimes they get flaky on me. I have found that if I'm only using one thing for a long time I'll plug that directly into my computer and the problems go away. Each port is supposedly able to supply 500ma but I've found that in real life it isn't exactly true through the hub. My GPIB converter pretty much always needs to be in its own port if I have more than one instrument attached or a long cable on it. My RS-232 converter will sometimes act funny if I print while it's working (like printing programmatically with a VI).

They are convenient but there are compromises that have to be made.