Question about usb in labview

[GabrielaK]

Hi Kim,
without having it tested with a general purpose USB device, the tests with our own hardware have shown that controlling an USB device via the FTDI dll is not faster than using VCP. If you can live with the fact that your application uses a virtual com port instead of "whao that's real USB" 😉 I would say using VISA read and write with VCP should be the best solution for you. This also gives you the chance to use your application under a non-windows environment as VISA is cross-platform, but dll calls are not.
Please correct me if somebody has other results.
Best regards,
Gabs

[Dennis_Knutson]

Kim,

Our little widget is just controlling a solid state relay so all I do is a VISA Write of either a 1 or 0. Pretty simple. I've not done any testing of the transfer rate but I know that FTDI claims the dll is much faster. I've attached all of the VIs that were written to access the dll during the evaluation. I can't make any claims about how well they all work.

Gabs,

You make a good point about cross-compatability with VISA but in order for the FTDI to appear as a serial port and LabVIEW using VISA, you need the VCP driver and FTDI only has windows versions. They do have Mac and Linux versions of the D2XX driver.

Message Edited by Dennis Knutson on 09-14-2007 07:13 AM

[GabrielaK]

Hi Dennis,
oh, that's a point. I didn't know that. Well, still it might (under Windows) be easier for Klm to use the VCP instead of calling the FTDI dll. Thanks for correcting me, Dennis!
Best regards,
Gabriela