Re: [CAD_CAM_EDM_DRO] Parallel Port Pins

Hi Brad,

For most controller programs, the step pulse has a short duration
(usually active low), that will be generated at a specific rate dictated
by the number of steps/inch and the feed rate wanted. The number of
steps issued is calculated from the distance the axis is to travel, and
the steps/inch of the hardware (mill/motor/leadscrew).

This pulse "stream" from the parallel port "step" pin will also probably
start off fairly slow, and accelerate to the feed rate, and then
decelerate, finally stopping when the required number of pulses have
been generated.

The pulse width is determined by the software, and must meet the
requirements of the stepper driver (hardware). Often about 10uS in
length. The direction pin will be set high or low, depending on the
direction of the move.

Simply stated, the driver makes the stepper take a step for each "step
command" it receives from the controller program. (Microstepping may
cause the drive to actually take "baby steps" for each commanded step).

The data sheets for the driver hardware will usually define the step and
direction signals required of the controller software.

HTH

Alan KM6VV


Brad Woolley wrote:

>
> Hi,
>
> I'm still a little confused with the output from a parallel port
> (KCam, but I'm sure others are the same), looking at one axis, I see the
> three pins Pulse, Direction and Enable, Direction is pretty obvious on or
> off indicating forward or reverse, I assume the enable indicates that the
> motor is to be activated, but what information does the pulse give me, is it
> simply counting the pulses while the enable bit is set, or is there some
> form of bit conversion to give me a number, either way how do I know the
> pulse width etc.
>
> Can anyone point me in the direction of somewhere to explain this, I
> have searched the internet without any success in finding an explanation.
>
> Thanks in advance.
>
> Brad