Using a meter other than a 3468A with HP-IL?

[4ster]

I am making a portable test station using a 3468A meter, a 41 and my HP-IL printer. Currently the plan is to put all the equipment, except the multimeter, in a pelican style case. To make things more portable, it would be better if I could ditch the meter and just use a small panel meter inside the case to sample voltages.

Is there a way to get other voltmeters to talk with the 41 over HP-IL?

I have a 82166 Converter and a 82164A RS-232 interface that I could use to get data into my 41 if I can get the panel meter output something useful for the 41.

Boring background to explain why I am asking the question:

I recently bought an HP 3468A with some helpful input from folks here: Thank you, it helped me to pick a reliable unit that I am very happy with. Being able to automate measurements and process them on my 41 is very handy (and fun to have the old 41 do new -to me- tricks).

My first project with the voltmeter is a test procedure for testing oxygen sensors (cells) in a rebreather. Scuba diving can be away from civilization for an extended period of time so a portable device to test the cells will be useful.

The basic concept is that cell output in mili-volts is measured in oxygen at 1 atmosphere: From that, expected mili-volts are calculated and compared to actual cell outputs in .21 to 2.00 ata of O2 using a pressure pot pressurized up to 1 atmosphere (2 atmospheres absolute).

The rebreather holds 5 cells and I take measurements of each cell at 7 different partial pressures of O2. This checks that the cells are responding correctly in the range they will be used and can show cells that are about to reach the end of their useful life.

I've written a 41 program that creates a data file from the test and am about 50% complete on a program that reads the data file and prints out a report for each cell. This will be far superior to my current procedure where I record data by hand and then enter it into a spreadsheet for a report.

I usually reside in the shallow end of the pool when electronics are involved and this is a little deeper than I can handle without some direction. If it is relatively easy to incorporate measurements from a modern meter it would be worth it to me to get everything in one package.

Steve

[Garth Wilson]

This may not be quite what you were looking for, but what moved me from TI to HP was the HP82169A HPIL-to-HPIB (IEEE-488) interface converter which opens you up to a nearly unlimited number of models of instrumentation you can connect to the 41. It is essentially transparent, making the individual pieces of equipment appear to be on the HPIL, except that you use manual addressing, for example:

Code:

137  22
138  SELECT        \ Get ready to talk to the HP3457A 6½-digit DMM again.  (22 is the bus address of the DMM.)
139  "ACV;R,5,.02" \ Tell it to get ready to measure AC voltage with a maximum of 5V input and give .02% (1mV) precision
140  OUTA          \                                                         (This sets the range and number of digits.)

If you have the 82164A (or FSI-164, almost the same thing but with a minimum of two RS-232 channels and a maximum of eight, not just one), you can cobble together things on the workbench that would be much smaller, lighter, and lower-power than a nice piece of equipment in a big case. It takes more effort though. The typical approach would be to use a microcontroller, and since the microcontroller's A/D input will probably be 8 or 10 bits from 0 to 5V, you'll use an op amp to scale the input from the millivolts put out by your sensor to the volts required by the A./D converter, and possibly offset it as well if necessary. The op amp's input offset error and other specifications will need to be up to the job of course.

[TASP]

If I am understanding what you want, just a few electronic items (op amps, resistors, transistors, etc.) to output a +5 on 3 different lines corresponding to;

too high millivolts

too low millivolts

just right millivolts


and then use the 82166 and watch for 0-0-0-0-0-0-0-1 or 0-0-0-0-0-0-1-0 or 0-0-0-0-0-1-0-0 depending.

And you could add 4 more lines if you wanted;

just barely too low

just barely too high

just in spec high

just in spec low


as I understand it, you already know the correct readings, use the 3468 to calibrate the compare gizmo, and then you'd have something small, battery powered, and just what you need.

[hp41cx]

[TASP]

You realize posting a pic like that on a site frequented by CAS sufferers might be a tad provocative ??

[4ster]

(11-10-2015 12:08 AM)hp41cx Wrote:  

So, is that for sale? ;-)

Steve

[Sylvain Cote]

(11-10-2015 01:02 AM)4ster Wrote:  So, is that for sale? ;-)

Is it ? Yes ? Mine! Mine! LOL!
Joking aside, if you ever decide to sell this item, you will have a rush of interested collectors at your heels. I known, I will ! 8-)

[hp41cx]

They are not available for sale.
It was only posted a picture of one of my CMT-300 to display another alternative for those measurements

[4ster]

I remember making the decision years ago to NOT buy a CMT-300 when I was given a Fluke by a friend from Fluke. I wish my older self could speak to my younger version! I found the CMT-300 manual on line - looks like it would fit the purpose perfectly.

[TASP]

I bought quite a few items back in the '80s, and sadly, missed some opportunities too.

I suppose, overall, I did fairly well, but I don't even remember seeing an ad for a CMT 300. I'd like to think if I had, I would have ordered one.

I remain amazed however, I had the presence of mind to get a Zenrom, and to not lose track of it over the years. Breaking my CGP115 was annoying, but it wasn't an HP gadget in the first place, so there's that. And 7470s are better and still available today, so I'm OK there.

I realize my triple XFun/Mem was dearly bought, and now is somewhat useless on the flagship 41CX, still, it's a David White conversion, and I'm very pleased to have it in the collection.

I'm realizing despite using my HP25 a great deal before I bought my first 41, I have lost all the programs I wrote for it. I recall wiring an external switch to the R/S key and writing a simple counting program to keep track of an equipment test at work back in the '70s. I realize it was a very simple program, and I can write another, but I'm sure it won't be 'exactly' the sequence I used nearly 40 years ago.

I've lost my HP25 security cradle too, although I think I still have the key.

[Frido Bohn]

Just to add my 2 cents: This project may be set up with a PIL-IO board of J-F Garnier and an Arduino. Thus, you would not have to rely on "historical" equipment.

[4ster]

(11-10-2015 10:03 AM)Frido Bohn Wrote:  Just to add my 2 cents: This project may be set up with a PIL-IO board of J-F Garnier and an Arduino. Thus, you would not have to rely on "historical" equipment.

Yes, while that would be the smart way to do it, it requires a skill set I don't have. I'm challenged enough writing a HP-41 program that does what I want it to do.