Newsgroups: comp.sys.hp48

> I saw your post regarding cable problems in comp.sys.palmtops.  In it you
> mentioned a data acquisition module which could be used with a HP48SX?
> If its not too much trouble I'd love to hear some details about this module
> as it sounds like just the thing I've been looking for.  Any info at
> all will be greatly appreciated.
> 
> regards.
> 
> <name deleted>

Sure, glad to oblige.

I got to do beta testing on the HP48, and one of the things I tested was the
grunt-level user commands in the I/O menu.  I was a process engineer at the
time, and was interested in using the 48 to monitor plating tanks, developer
baths and other such goodies.

At the same time, I was building a ductility tester using an HP9816 as a
controller, and I was looking for some small and cheap RS-232 data acquisition
hardware.  My search led me to a collection of blue hexagons, each about the
size of a hockey puck, manufactured by DGH in New Hampshire, and OEM'ed by
Omega Engineering and MetraByte Corp.  (MetraByte no longer carries them).

Each hexagon is a self-contained signal-conditioning module, consisting of
an ADC chip, a UART, an EEPROM and some custom stuff.  It communicates
to the outside world via RS-232, RS-422 or RS-485 (the latter two are
variations on the 232 standard).  I was using RS-485 so I could connect the
modules in parallel, but DGH designed the modules so that the RS-232 ones
could be connected daisy-chain style, and only use one serial port on your
controller.  It's what HPIL should have been, and a very good idea.

I hooked my RS-485 modules up to a 232/485 converter, and from there to my
HP48SX.  Everything worked great.  The guys in Calculator Marketing bought one
to play with (cost is $200 - $250 each), but they couldn't make it work.  Two
problems:

1)  All UART settings are contained in an EEPROM in the module.  The module 
    comes from the factory preset to 300 baud.  The 48 doesn't go down to 300
    baud, so you have to use another computer to set the module for HP48SX
    communications.

2)  The module won't recognize a signal strength of less than 5.0 volts (I 
    think), and the 48 tramsits at 4.2 volts.  We had to build a power booster
    to get the two units to talk to each other.  In fact, Joel Kolstad (of
    the Internet) and I were working on a teeny battery-powered booster, but
    then I moved from Oregon to Colorado, and I haven't had time to work on
    it since then.

    An alternative is to buy a commercial RS-232 buffer/repeater from Omega or
    DGH or elsewhere.  Retail cost is $99.  Works fine.

In spite of these two problems, I still strongly recommend these devices for 
data acquisition with either the 48 or the 95.  I would suggest that you call
or write DGH directly (tell them I sent you).  Here are phone #'s, etc.



DGH Corporation
P.O. Box 5638
Manchester, NH 03108

(603)622-0452

Omega Engineering, Inc.
P.O. Box 2284
Stamford, CT 06906

(800)826-6342 sales
(800)872-9436 engineering and technical assistance
(203)359-7874 to order a set of Omega catalogs


If you have any other questions, feel free to write me again.  I won't
guarantee a speedy reply, but I'll get back to you eventually.

--
Regards
Ray Depew
Hewlett Packard ICBD, Fort Collins, CO
rrd@hpfitst1.fc.hp.com

From: rrd@hpfcso.FC.HP.COM (Ray Depew)
Date: Tue, 1 Sep 1992 14:56:28 GMT
Subject: Re: PCX -> GROB conversion
Organization: Hewlett-Packard, Fort Collins, CO, USA