selecting motion hardware

[jcarmody]

Hi,

I need to select a small motor to feed string into a process.  I've looked at NI's offerings, but they're all rather large and I don't know where to look next.  I need to feed a light cotton wick (about 1/4" diameter) with very little tension so it doesn't need to be large.  I've got a servo motor from my Parallax kit, which I believe I can control with a digital output, but I'm not sure that's a good choice.

Could you suggest hardware I could use and control from my LabVIEW program?  I don't have any experience designing motion control systems but I have programmed using NI Motion drivers.

Thanks,

Jim

[Daklu]

I've got a servo motor from my Parallax kit, which I believe I can control with a digital output, but I'm not sure that's a good choice.

Why not?

[jcarmody]

Why not?

Let me think about that...  My first thought was "Because it's from a toy!!!".  It might be Ok if my DO can power the servo without any external circuits, I'll have to check. I guess it would be Ok even if I had to wire up a driver circuit. It just feels like a cheap way out of designing a robust system. It certainly would be an inexpensive solution.

Thanks for posting,

Jim

[crelf]

I've used Parker motors and amplifiers before, and they worked great. We even had a special motor wound for a project that required higher speed + high torque and I remember the rates being quite reasonable. You can control the amps with NI motion cards, as well as plenty of other means - the amps have serial (RS232 + RS485), USB, analog 0 to +10V, digital pulse train... and more! As I recall, the last time I used them I talked to them through a Parker controller - but I'd sworn that I'd never do that again. The controllers work great, but they're not compatible with NI-Motion, and we had to write drivers (well, a driver layer) - there's no sense in reinventing the wheel, and I've found NI-Motion to be pretty good in the past. Lots of motion component vendors will try to tell you that their brand of motors only really work well with their brand of controllers, but in my experience that's been sales talk. If a sales person tries that on you, tell them that if you can't get their motors and amps without their controllers, then you'll go get them from someone else - they'll change their tune pretty quickly. That said, if you're not experienced in motion and you can't get something to work, you might find it an uphill battle with the motor + amp vendor blaming the NI controller, and vice versa...