Phidget Servocontrol -- PWM Question

[daco]

I am a novice with labview. I have a device from Phidget (www.phidgets.com) that is a USB device. The device controls a servomotor.

I want to be able to generate a PWM via labview to control this device. But since this is a USB device do I need some special hardware to talk to the USB device?

The Phidget website does have some sample labview programs that I have been able to get to work but they seem to use activex to talk to the servocontroller.

Is there any other way to interface with this servocontroller? Also, where can I find some sample labview programs that output a simple PWM?

[Jochen]

Daco,

you should compare USB to an internal PC bus like PCI rather than to an RS232 port. For devices plugged into the PC for most people it's clear that they need a driver from the vendor of these devices to be able to communicate with them. In many cases a driver is available as a DLL but sometimes device vendors provide also ActiveX controls as an API for the driver.

Due to the protocol overhead ActiveX doesn't provide the best performance but depending on the implementation the interface might be pretty easy to use. If there is a well documented DLL available you could also use this DLL in LabVIEW (Call Library Node) as a DLL call is typically much faster than an ActiveX call.
In LabVIEW there is also an option to talk directly to the USB by using NI-VISA calls but then you would have to implement the complete protocol that's used by the Phidget device and as there is already a driver available I wouldn't recommend this option.

Best regards,

Jochen Klier
National Instruments Germany