CAD CAM EDM DRO - Yahoo Group Archive

Re: Servo amp using pwm+- with mach 2

Posted by caudlet
on 2004-06-16 14:11:44 UTC
--- In CAD_CAM_EDM_DRO@yahoogroups.com, "callcbmf" <callcbm@d...>
wrote:
> I just purchased a Two API Brushless Servo Motors w/ AMC Amps and
> Power Supply in the right up it say it uses pwm+- and I wonderd if
> any body has use this setup or can it be changed to step and
> direction.
> I would like to use mach 2 with out much trouble. This is being
> used
> on a plasma table
> Amplifiers: http://www.a-m-c.com/download/b15a.pdf
> Motors: http://www.apicontrols.com/newapi/products/turbo_mbt23.html
> the part
> number for the motor is MBT-N231 and B12A6 for the amplifiers. More
> information for these setups can be obtained at the websites below.
> http://cgi.ebay.com/ws/eBayISAPI.dll?
> ViewItem&item=3820060149&sspagename=STR
> K%3AMEWN%3AIT&rd=1
>
> I just paid for the license for mach 2 I like the program if I can
> get these
> motors to work. the next Item is thc from Campbell's Designs
> Thanks Randy
> P.S Yes I'm a newbe


This appears to a standard Servo amplifier that uses the motor tach
(or it appears motor current optionally) to get velocity feedback.
The commanded velocity from the computer is compared to the motor
velocity for speed. The Amps need a +/- 10VDC control voltage input.
I will have to defer to someone else in the next part and that has to
do with positional feedback. I don't know if the three hall sensors
can be used like an encoder or just for commutation. The amp does
not/will not take a PWM control signal in.

In order to get from MACH2 (step and Direction) to +/- 10VDC control
voltage you need two things: A circuit to convert the Step and
Direction PWM output to +/- 10 and a feedback path (positional) to
give you an error voltage. The circuit I am aware of is the Rutex
R997 Step to Servo control card but a quick transversal of their
current web site no longer shows that as a product. The specs are
still in the download section. If they have quit making that card
then the options start to slim down. They have a brushless DC motor
control card but it still needs feedback from a digital encoder
rather than the tach. It would take the place of your amps you bought.

Maybe soembody else knows of a Step/Direction to +/- 10 analog
converter?

Jon at Pico has a servo card that may drive your brushless amps but
his cards work only with EMC and the THC for MACH2 will not work with
it.

Discussion Thread

callcbmf 2004-06-15 15:22:44 UTC Servo amp using pwm+- with mach 2 caudlet 2004-06-16 14:11:44 UTC Re: Servo amp using pwm+- with mach 2