Re: Changing Parallel Port Pins

[Jon Elson <elson-at-pico-systems.com>]

Rick Mann wrote:

> I've just installed EMC BDI 2.16. Looking through the docs, it seems that,
> to change the pin usage on the parallel port, that I need to modify the
> source.
>
> Can someone point me to the correct source file to change? I need to assert
> three pins to enable the three axes on my mill.
>
> If it's possible to do this vi a .ini file, I'd love to know how. I didn't
> notice any parameters that might change the pins in the docs.

The ini file, at the end, has the specifications for all the auxilliary I/O
(machine on/off,
spindle, coolant, etc.)  The bits are specified as an index, so 0 means the
first bit,
1 means the 2nd bit, etc.  Sensing of the Estop input is there, too.  Look at
the end
of the file, in a section called [EMCIO].  One standard setup has
ESTOP_WRITE_INDEX = 10
which puts the estop output signal on the 3rd control output pin (0..7 are the
standard
data lines).
If you really need to have 3 separate outputs, you will need to hack one of
the
routines in /usr/local/emc/src/emcio such as bridgeportaux.cc
You will see that it sets a bit as specified by the parameter
ESTOP_WRITE_INDEX
to a state set by ESTOP_WRITE_POLARITY for going to ESTOP, and to the
opposite polarity for coming out of ESTOP.  3 calls to extDioWrite with
appropriate
parameters should make 3 bits on the parallel port change state.  (Note that
the program
monitors the state of these bits, so if the specified bit diesn't change to
the right state,
it will start writing error messages dozens of times a second.)

There is some info on the mapping of these index values to port pinout in the
www.linuxcnc.org
documentation.

Jon