RC Servo control using FP-PWM-520?

[Bikeracer]

I was wondering if anyone has any experience using Labview (7.0) to control a Fieldpoint FP-PWM-520 module to drive small RC aircraft servos? I am a chemist and I am very inexperienced in advanced Labview programming but I am trying to make good use of the equipment I have available. I want to use the servos to automate a remote radiochemical synthesis ( as a syringe driver)  I have read that I may need a pulse width of up to 2 ms to drive this servo. This may kill the project right away since the output of the FP-PWM-520 seems to only go up to 1ms. Is that so? Anyway I would also very much appreciate any example code with LV 7.0 that may show this type of control. I apologize for my lack of knowledge in coding. I hope I can sort of reverse engineer someone elses code and learn a few things in the process. Thanks very much for any and all help!

                                                                                                               Steve Toorongian

[Matthew_Williams]

We tried to use a cFP PWM module to drive RC servos and it almost worked.  My recollection
is that we could move the servo as required but the turn on and turn off issues killed the idea
for our application.  There is no way to control when in the PWM cycle the module turns off
it's output, therefore the final position of the servo (after you turn off the pwm output) could
be anywhere.  Subsequently, turning on the pwm would cause it to jump from wherever it
stopped after turn off to the new position.

Our solution was to develop a small microcontroller based pwm driver.  This gives us complete
control over the pwm output as well as a bunch of remote I/O points.  We multiplex up to
64 of these devices onto a serial port on the fp controller.

If the turn on and turn off issues aren't a problem I can dig out some of our testing .vis.  They
are not finished applications, just 'move the servo' kind of things.

The microcontroller driver was developed under contract so I can't offer any of that stuff
without permission.  Let me know if that would be of interest.

Matt

[Steven_T]

Steve,

There is an example in the NI Example Finder that will let you set the period and duty cycle of a pulse width.  You can get it by accessing the Help-Find Examples in LabVIEW.  The name of the example is Pulse Width Modulation.vi.  This example allows the user to select a different period and duty cycle for each channel on the PWM-520.

Steven T