Re: [CAD_CAM_EDM_DRO] help with controlling a motor?

linwoodcnc wrote:

>I really just need to make a computer running windows, be able to start and stop a motor
>connected to a chain, and receive info from switches (on-off) for feedback from the
>movement the motor has done to the chain. but I'm stuck because i've never done such a
>thing. so i'm guessing you use the serial port, with that in mind, do i need to get like a PIC
>controller and figure out all that to make a device between the computer and the motor/
>switches or can i splice a serial wire in someway that it can do all of that? (10 physical
>switches + 1 motor)
>
>
>

I think you could do this much more easilyt from the parallel port.
The basic parallel port has 8 data bit outputs and 5 (I think) inputs.
You can connect one of the data outputs (pins 2-9) to the - terminal
of a solid state relay. Connect the + terminal to pin 1 of the game
port. When the data bit output is set to a zero, the SSR will be turned
on. The AC terminals can be connected in series with the motor
and the AC line.

You need ten inputs? That is a little bit of a problem, as that runs
close to
the limit of the parallel port. But, you can use a bidirectional parallel
port as input, to get 8 inputs, and use 2 other status input lines to
get the
10 inputs you need. There will still be 3 control output lines, one
of which can be used to control the motor. You should be able to
connect your switches between ground (parallel port pins 18-25)
and the input signal pin. You might need a resistor of 1 K Ohm or
so connected between the signal pin and the + 5 V on pin 1 of the game port
to make sure the computer reads a 1 from the input pin when the switch is
open. You might get the book "Parallel Port Complete" by Jan Axelson.
It goes into great detail on how to do things like this, and how to program
it from basic and other languages.

You don't seem to need a PIC or other external microprocessor for this.

Jon