Thanks for the reply. I have just got the code working without the UsbPt104Enumerate function There is a mistake in the example VI for USB comms where the USBPT104Open DLL call has an I32 wired to Serial instead of a proper string constant of the Serial No. This lets me successfully communicate with...

I'm trying to use two of these devices in parallel over USB but need to use the UsbPt104Enumerate function to properly address them. One device works fine as an example is provided. I've tried to follow the programming guide http://www.picotech.com/document/pdf/usbpt104pg.en​-2.pdf but frankly I'm n...