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Great question! One of the most technically interesting I have seen on the OptoForum. These days everyone is talking PACs and
Ethernet 10/100 but there is still a whole world out there who just want to
activate a digital output from a PC parallel port, and the human race is fast forgetting
even how to do it.
There is also no way
cheaper to connect an Opto22 I/O module to a PC software application!
The PB24HQ I/O mounting rack can accommodate
up to six Digital Quad Pak I/O (Gmodules for a total of 24 I/O channels. It
uses a 50-pin male header connector for connection to computer parallel I/O
ports via a 50-conductor ribbon cable. So the first thing you will need is a 50
way ribbon cable! The following datasheet specifies standard lengths available from Opto22 and a list of component suppliers if you want to make your own. http://www.opto22.com/documents/0490_Cables_data_sheet.pdf
So how does the ribbon cable fit
into the standard parallel port of your computer? The simple answer is that it directly it doesn’t.! Assuming that you are using the
PB24HQ base board and have a 50 way ribbon cable, you will then need a suitable
interface card for your PC. Opto22 produces two suitable cards.
PCI-AC51 PCI bus to Pamux bus
adapter
AC28 ISA Bus to Pamux bus Adapter
There are two reasons for using such
cards.
1) A standard 25pin parallel port only
allows a maximum of 8 I/O to be controlled (D0 to D7) while an interface card allows
up to 24 I/O to be controlled.
2) If you connect things up wrong or
have a voltage spike, damage will be limited to the card and not extend to the
computer motherboard etc, which will probably need to be replaced.
You can find out more about these
cards from the technical documentation available on the Opto22 website,
including a free downloadable software toolkit that works with Windows2000 and
XP, including examples for Microsoft Visual Basic® 6.0 or Microsoft C++® 6.0. For
details on installing and using the PCI-AC51 and its toolkit, see Opto 22 form #1459, the
PCI-AC51 User’s Guide.
But if you really want to connect
directly to your parallel port and connect to a maximum of 2 Quad modules on
the PB24HQ then download the specsheet. The schematic shows the relation of
pins to signals.
http://www.opto22.com/documents/0479_Quad_Dig_16_Ch_data_sheet.pdf
I would then recommend an excellent document available on the internet entitled “Parallel Port
Interfacing made Easy by Tomi Engdahl”, which explains everything you need to know,
even a web interface! Its one of the
best documents on the web and very interesting reading.
http://www.epanorama.net/circuits/parallel_output.html#circuithow
Have fun.
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