Input Board

Hi everybody,

I am looking for a board that can read the conditions of about 100 switches
and transmit them to the PC. I found something here:
http://www.alfasprint.be/InputBoard.htm
The board has 32 inputs, but the thing is that it costs 100 Euros (about 125
US-$) a piece.
Is this price too high - what do you think? Or do you know alternatives?

Any help appreciated!

Regards Seb

 

If you don't mind building a little circuitry, how about the
printer port? You can read 5 bits at a time from the
status port, and use the data port to select a multiplexer
channel. This will allow up to 256 x 5 channels. Or you
can use bidirectional mode and read 8 data bits at a time
from the data port, with a pin from the control port to
latch the multiplexer.

This will work with simple I/O commands on Win9x or
earlier systems, but may need a special driver for
NT/2K/XP systems.


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

Hi everybody,

Hi, Seb. First, if you are considering just interfacing with switches, have
you looked at using a switch matrix? You can read up to 100 switches with a 10
X 10 switch matrix, which will limit your I/O requirements to 10 input lines
and 10 output lines. You will need some diodes and pullup resistors (you
should use Schottky diodes to minimize voltage drop, especially if you have any
distance between the switches and the PC) as well as a circuit board or
perfboard to mount the components and provide termination for the switch wires.
The software overhead for reading a switch matrix is minimal.

The page you specified reads like the module has optoisolation of the inputs,
as well as built-in terminal blocks. For the price, it seems like a very good
value, but I'm not sure you really need 3 or 4 of these just to read 100
switches.

Good luck
Chris

 

Seb,

Looking at the option that you looked at, I'm still not particular
clear how you ultimately interface the board..? It mentions
synchronous serial and parallel, I'm not sure if that's enough
information for you to get started with.

I wanted to recommend something that our company provides:
http://www.tern.com/rengine.htm
http://www.tern.com/p100.htm

The R-Engine is the core, C/C++ programmable controller. x86-based,
clocked at up to 80 Mhz, it supports 3 RS-232 ports, up to 32 I/O
pins, etc. The P100 can then provide an additional 96 programmable
I/Os. Total price for the system: about $198.

The board's certainly more powerful as well. With a full 1 MB of
memory space and fully C-programmable, you can implement a wide range
of additional embedded control behavior. The interface to the PC
would be straight-forward: you can set up a serial port connection
with your PC's com port, and control the board through a simple
terminal.

I'm going to keep it relatively short here. If you have any interest
or questions at all, do drop me an email at the address above!

 

Boondog www.boondog.com has a 24 port board (based on the 8255 chip) for $69
assembled and tested. Don't know how many you can put in the same PC.

More about me: http://www.jecarter.com/
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