Help! Anyone familiar with BCD signal output?

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2 total messages Started by Bruce T. Blakely Thu, 26 May 1994 00:28

#38

Author: Bruce T. Blakely
Date: Thu, 26 May 1994 00:28

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We have an instrument (a luminometer) that, acccording to the manual, has
a "BCD signal output suitable for interface with Apple II and other 
compatible data systems." The connector for this output is a Centronics
style connector. However, we do not have an Apple II.

Is there any (fairly simple) way that we can feed this BCD signal into
a computer? Preferably, into the serial port of a Mac, or into the serial
or parallel ports of a PC? Currently, we have to record the instrument 
readings by hand; if we can get it to talk to the computer, we can dump the
output into a file for printing or into a spreadsheet for manipulation.
(It would be fine to connect it to a printer, but if we can get it to
talk to a printer, we could probably get it to talk to computer).

The machine also has an analogue output, for what its worth...

Is there a better newsgroup on which to post this question?

Thanks for any help,
Bruce Blakely
blakely@cmgm.stanford.edu

Re: Help! Anyone familiar with BCD signal output?

#39

Author: Cedric Walker
Date: Thu, 26 May 1994 11:34

34 lines
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In article <2s0qek$8r0@nntp2.Stanford.EDU>, blakely@leland.Stanford.EDU (Bruce T. Blakely) writes:
>We have an instrument (a luminometer) that, acccording to the manual, has
>a "BCD signal output suitable for interface with Apple II and other 
>compatible data systems." The connector for this output is a Centronics
>style connector. However, we do not have an Apple II.
>
>Is there any (fairly simple) way that we can feed this BCD signal into
>a computer? 

BCD stands for binary coded decimal. 4 wires (bits) on the connector are used
to encode each decimal digit output. It was a handy interface back in the
days of nixie tubes and roll-your-own LED displays. An output value of, say,
255 was represented as 0011 0101 0101 (12 bits, 4 per digit).

>
>The machine also has an analogue output, for what its worth...
>

It wouldn't be hard to write a BCD-to-serial translator on a little
Motorola 'HC11 board or similar, as long as you know the pinouts on
the Centronics connector and as long as they're TTL so you don't have
to build a zillion level shifters. But since your sensor is most
likely an analog device with an analog output, imho you'd have
an easier time going into an A-D convertor on your Mac. If the 
output of the luminometer changes slowly as a function of time,
you can get by with one of the <$300 A-D convertors that plugs
into the serial port of the Mac.

Good luck.

Cedric Walker
Tulane University
New Orleans, LA

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