Re: send more than 8 bits with parallel port

On 20 Feb 2006 18:13:06 -0800, "jccorreu@xxxxxxxxx"
<jccorreu@xxxxxxxxx> wrote:

We're using a parallel port for motion control. We're building the
hardware logic for the device we're going to control, and want to be
able to send a packet containing 2 bytes of information, and let the
circuit we build translate it and drive our device.
I know that parallel port was designed with a standard for printers,
using a 1 byte data regisiter. What I want to know is how to hack it
so that I can use more than pins 2-9 to output data from our computer.
The control register has pins 1, 14, 16, 17. I take it that i can set
whatever I want to these (TTL), and on the device end, translate it
however I choose. So i need 4 more pins from something.
I know that pins 18-25 are ground. I think that makes them out of the
question, though if anyone knows how I could use some of them to
transmit data I'd be interested.
The info i have on status register says its read only, and that data
written there is ignored. What ignores it, the computer or the
printer? Is there a way to get around it?

thanks
James


Others have answered the hardware aspect of your
question. However, note that if you plan to use this
on PCs running Windows versions later than 9x,
you will have to use a special ring 0 device driver to have
access to the printer port. (GIVEIO and USERPORT are
two that I have heard of, put haven't tried myself.)
That might be one advantage for using the serial
port, which can be accessed through more-or-less
standard Windows API functions.

Another thing to think about is that parallel printer ports
are rumored to be slated for extinction... but then again,
aren't we all!

Best regards,



Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator
.

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