Re: Simple Parallel Port controller

--- In CAD_CAM_EDM_DRO@y..., JanRwl@A... wrote:

> Eric:
>
> You could use just ONE bit of the eight of the parallel-printer-

port to turn

> that ONE relay on or off, or, you could even use some cascaded

decoder-logic

> (74HCT4514, for example) to control up to 255 separate relays. But

NO ONE

> has given you a hint how to "do that" from software!
>
> If you are using simple BASIC, you can OUT 888,n (888 is the

decimal address

> of the printer-port, or, $378 in HEX). If you connect your relay

to bit-0,

> then OUT 888,1 makes that bit "go high", and OUT 888,0 makes it

(all-8) "go

> low" again.
>
> The solid-state relay another in the group suggested is a sure-fire

way to do

> it, but you COULD use HCT logic and "any" SSR, or even an

electromagnetic

> relay, if you used the right "sink driver". But I have no clue how

much

> "electronics" you know.
>
> In a BASIC program, when you come to an "OUT 888,n", that "n" will

be put on

> the port (binary equivalent of zero or 1 through 255) until changed

by a

> later "OUT...".
>
> For example: 10 OUT 888,1
> 30 OUT 888,0
>
> will "toggle" bit-zero for a couple of microseconds or so

(depending upon how

> fast your particular computer is). Or, if you add a line 20 FOR

D=1 to

> 10000:NEXT, it will "stretch" the "on-time" of bit-zero (making the

10000

> larger will stretch it proportionately more, of course).
>
> If you do NOT included line-30 above, that bit will REMAIN high

until you

> turn off the computer, or some other program changes that bit!

This can

> confuse things if you have little experience with such, and/or,

no "pilot

> lights" on the 8 port-bits.
>
> Lotsa luck! Jan Rowland, Old Troll
>
>
>
>
> [Non-text portions of this message have been removed]

I am good on the mechanical side but I need as much help as possible
on the electonic's side. What you are talking about is what I am
looking to do. I like the simple relay and pp off/on switch approach
for now. I am pretty good in visual basic programming and have a
program I downloaded from somewhere that can be used to control RC
servo motors thru the paralell port. This is where I was looking to
start from. My biggest question is are there 2 pins on the pp that I
can hool to to get my switching for the relay? And if so what kind of
power consupmtion requirments do I need to stay under for the relay
as to not damage my pp? Do you have any sample code for just turning
off and on one pair of pins?

Thanks
Scott