Re: This is my same confusion (Port#2 re-visited)

["Ian W. Wright" <ian-at-iw63.freeserve.co.uk>]

----- Original Message -----
From: "Patrick Riedlinger" <patr-at-precidesign.com>
To: "Multiple recipients of list" <emc-at-nist.gov>
Sent: Tuesday, May 07, 2002 7:15 AM
Subject: Re: This is my same confusion (Port#2 re-visited)


>
> First I want to thank Marc Christensen, Ray Henry and Tim Goldstein for
> attempting to tutor me in EMC I/O theory. But Jason put in the same
snippit
> from the same INI file that confused me. Please note below:
>
> ESTOP_SENSE_INDEX         =     1
>
> This means that S1 on this particular parallel port is an input, right?
>
> Ok, now observe this:
>
> SPINDLE_FORWARD_INDEX     =     1
>
> This implies that the same D1 line is being used as an output.

I think you are confusing pin settings with control actions. What the '1'
setting in the .ini file means is that you are intending the output
(wherever it goes) to be 'Logic High' or that the input should be considered
'ON' if it sees a 'Logic High' (i.e. a +5v voltage or logic 1) at the
relevant input pin. If you change this setting to '0' in the .ini file, the
input or output will react to 'Logic Low'.

Best wishes,
Ian
--

Ian W. Wright
Sheffield, UK