geller@bnlux0.bnl.gov (joseph geller) (02/13/91)
Is anyone using the HP 48SX for data acquisition? I'm thinking of using mine to do some data logging via the RS 232. I only need 4 or 5 data points (12-14 bit) every one to 5 minutes. I'm giving some thought to some sort of used chart recorder with RS 232 output (lot's of them have it now) or building a simple Analog to Digital Converter circuit to do the job myself. The only commercial unit I've seen specifically for the 48 was in the Educalc cat. Is anyone on the net using that one? Some of the HP instruments used to be marketed for the 41. Does anyone know if they plan battery instruments for the 48? geller@bnlux0.bnl.gov
rrd@hpfcso.FC.HP.COM (Ray Depew) (02/15/91)
In hpfcso:comp.sys.handhelds, geller@bnlux0.bnl.gov (joseph geller) asks: >>>>>>> Is anyone using the HP 48SX for data acquisition? I'm thinking of using mine to do some data logging via the RS 232. I only need 4 or 5 data points (12-14 bit) every one to 5 minutes. I'm giving some thought to some sort of used chart recorder with RS 232 output (lot's of them have it now) or building a simple Analog to Digital Converter circuit to do the job myself. >>>>>>> There are some terrific units that will meet your needs, sold by DGH and by Omega Engineering. Actually, they're built by DGH and OEM'ed by Omega. I think technical support is the same either way, but.... ANYway, these are little blue hexagons, about an inch thick and less than 4 inches in diameter, called "Signal Conditioning Modules." Basically, they're a D/A converter, a UART, some glue logic and an EEPROM all wrapped up in a watertight box. They take 10-30 volts unregulated DC for power, and do all the power conditionnig themselves They come factory-preconfigured for 300 baud, so you have to hook them to a non-HP48 computer to change them to a baud rate the 48 can recognize. If I remember correctly, they go all the way up to 19.2 Kbaud. The I/O for them is written such that you can daisy-chain the RS-232 modules together (very much reminiscent of HPIL -- maybe what HPIL aspired to be). The RS-485 models are meant to be connected in parallel, through an RS232/RS485 convertor box ($99, or build your own). Either version uses exactly the same commands, and they're really easy to learn. For example, to read data from the first module in line, you send it the command "#1RD". THat's all. The only problem with them is that they can't read the HP48's low voltage signals directly. They're available with either RS-232, RS-422 or RS-485 interface, and I always used the RS-485 models, with a 232/485 convertor between the modules and the 48. The convertor seemed to boost the signal quite nicely. You can use the RS-232 versions just fine, if you build a little power booster to boost the 48's signal to something acceptable. Joel Kolstad built a really nice booster, and I was going to write an app note for HP for it, but his prototype is still sitting on my shelf (blush of embarrassment here). Prices range from about $200 for the voltmeter to about $400 for the frequency counter. If you send me email, I'll send you addresses for DGH and Omega. (It's on my list, Joel, I just ahven't gotten around to it yet!) There's a really nice book coming out soon, with a couple of cool programs about turning your 48's display into either a stripchart recorder or an analog meter ---- and turning your 82240B printer into a stripchart recorder. THe author is a close personal friend of mine. Please excuse the typos. I'm typing this in by modem, over a VERY noisy phone line. Regards Ray Depew IC's by Bill and Dave rrd@hpfitst1.hp.com
rrd@hpfcso.FC.HP.COM (Ray Depew) (02/15/91)
In hpfcso:comp.sys.handhelds, rrd@hpfcso.FC.HP.COM (Ray Depew) blabbers on
about some really nice Signal Conditioning Modules:
> [ etc. ]
I forgot to add the disclaimer. Don't construe my previous posting as
an endorsement by HP of the DGH/Omega SCM's. You can consider it an
endorsement by a qualified process engineer if you want, but i don't
speak for HP.
-- Ray
rrd@hpfitst1.hp.comakcs.dpenn@hpcvbbs.UUCP (David Michael Pennington) (02/16/91)
I'm an undergrad senior ee at Christian Bros Univ, my partner and I just finished developing a Data Aq system for the 48SX. This thing can be interfaced to any meter as long as the LCD is not multiplexed out. Were presently developing a design to interface an autoranging meter. software we have samples at about 1sample/800msec. If you are interested, write me at the address below. Once data points have been taken, you process the data as you like with the HP. We've gotten some nice results plotting Voltage/current lines for resistors... All data is transfered through the IR port, this thing can't damage the calculator hardware. If we every can get a working copy of the STAR assembler, the software would speed up immensely. Write me at... Mike Pennington 650 E. Parkway S. Box 72 Memphis, TN 38104