Labview Servos

[quizbiz]

I can get to one extreme but not the other extreme on the other side. I have values between 0 and 254. It won't let me put in negative values which I tried to do.

Also can someone explain the Scale Servo VI to me please? I have a feeling I should be using it but am unsure what it does or how to use it to effect the servo performance.

Thanks for your help.

[Greg McKaskle]

I think that the integer scaled VI for servos tends to be in degrees. The servo I've used it on went from 0 to 169 or 170. More expensive servos go to 200 degrees or more. I didn't use the scale VI, and I don't have the VIs in front of me, but I suspect they are to scale between the int degrees and the 0 to 1 scale common to the other APIs such as joysticks.

Greg McKaskle

[DavidGitz]

What we've been able to determine is that the servo's, unlike the jaguar's, range from 0 to 1 (default) with .5 being their center position. We also found that they wouldn't work at all without the 6V jumper installed. FYI, the jaguar range is from -1 to 1 (default).

[Russ Beavis]

Without that jumper installed in the Digital Sidecar (aka DSC), servos won't have any power. The jumper should only be installed in positions that are driving servos since speed controllers such as Victors and Jaguars don't need to have power supplied via the 3-pin PWM cable (they're entirely powered by the big V+/V- terminals).

In fact, some speed controllers output a 5V (or so) power supply on their middle pin for powering external electronics. Such speed controllers would back-feed the DSC if the 6V power jumper was installed (generally not a good thing).

Russ

[brianc217]

I think this will help my team a lot. We couldn't get the servos to work AT ALL but it looks like the problem is that 6V jumper.
Is there a manual somewhere that has all those little tips and tricks like that so we don't have to spend days trying to get a simple servo to work.
I will blame hardware as usual. haha. thanks.

[Alan Anderson]

Originally Posted by brianc217

...Is there a manual somewhere...

http://usfirst.org/frccontrolsystem

What you're specifically asking about is Chapter 3 Component Data Sheets. Section 3.5 is all about the Digital Sidecar.