Re: [CAD_CAM_EDM_DRO] EMC Spindle control Help!

paragon032003 wrote:

>Hello Group,
>
>How does EMC send Cutter spindle speed to the controllers?
>I.e. stepper = step/dir = 2 Pins from printer port.
>
>I have a variable motor controller board that is controlled by
>voltage.
>The input has 3 wires lets say A B C.
>
>Voltmeter Testing.
>
>A and C = 12V Steady
>A and B = Variable voltage 2.3 - 9.7 V Approx.
>B and C = Variable Voltage 2.3 - 9.7V Approx.
>
>When A + B carry low Volts, B + C are carrying high Volts and vice
>versa (I.E. they complement each other and are relative adding up to
>the total of 12V)
>
>The Higher voltage across B and C = Faster Motor Speed
>The Higher voltage across A and B = Slower Motor Speed
>
>So when B and C are reading max voltage the voltage to the motor is
>approx. 190V.
>
>BTW this is off of a very old CNC machine.
>
>What I am going to need to-do is have these voltages controlled via
>EMC + a circuit to produce the above output voltages.
>
>Does anyone have any idea what is required or what this circuit is
>called.
>
>

You need a Digital to Analog converter, and a software driver for it.
The PPMC board set I have for servo motion control does this, and produces
either -10 to +10 V for bidirectional spindle servos, or 0 to +10 V for
variable speed drives. It soundls like your ABC wires are normally
connected to a potentiometer (like a radio volume control). If this
is an isolated circuit, C can be connected to the DAC ground, and B
to the DAC signal. A is a +12 V source from the drive, and is not needed
in this application. If the drive does not have an isolated input,
there are
ways to make it isolated. If you need the full 12 V, there are simple
changes
that can be used to make the DAC produce those voltages.

My Universal Stepper Controller has provisions for spindle speed control.
If you only use 3 motion axes, the 4th axis can be set up to produce a pulse
frequency modulation signal that can be converted to a DC voltage. This
works with the BDI EMC right out of the box. There is also a spindle DAC
connector on the USC board that can be connected to an outboard DAC.
It takes a little software change to make that work, and I intend to dig
into
that shortly.

You can see info on these products at
http://jelinux.pico-systems.com/motion.html

Jon