[erase42]

Hi guys, I may have shot myself in the foot. I found a triple motor and driver set on ebay for what seems like very fair price. I looked up the driver specs, but was more interested in the volt/amp rating than control method since almost everything we discuss here is step/direction. Anyway the drivers are Advanced Motion Controls model 12a8k Here is a link to the teck page

http://www.a-m-c.com/download/datasheet/12a8.pdf

I guess my question is what do they look at for positional control? Are these something I can never use.

Another quick question is that the motors by Minertia have 4 brushes, Ive seen this on some starter motors and such but never noticed it on servos. What if any bearing does this have on their usefullness?

Thanks.
Ed

[Al_The_Man]

The common mode of setting these is for the torque or current mode, no tach required.
They are not positional in-and-of themselves, they operate in conjunction with encoder feedback to a Motion control system of some kind, they use analogue input so would need a step/direction convertor for this kind of control.
Its of little consequence to the drives whether the motors have two or four brushes, higher quality DC servo's are often equipped with 4 brushes.
Al.

[erase42]

what is involved with a step/direction converter and is that suitable for our standard cnc uses? ill do some reasearch but i appreciate your help.