Agilent 34401A Hidden 10mA AC current range - Page 1
Forum section: electronics / testgear

author: macboy
author_rank: Super Contributor
timestamp: March 04, 2014, 05:23:47 pm
content: I wonder if people know about this hidden 10 mA AC Current range. Normally, the ACI is limited to the 1 A or the 3 A range. The following command sent over GPIB (or I assume over RS232 after sending "SYST:REMOTE") will unlock the 10 mA range. It can then be accessed from the front panel or the bus, and persists over power cycle.To enable : "DIAG:POKE 25,0,1"To disable : "DIAG:POKE 25,0,0"

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 04, 2014, 06:43:36 pm
content: But does it actually work, or is it relying on hardware that isn't fitted?

author: sync
author_rank: Frequent Contributor
timestamp: March 04, 2014, 07:06:43 pm
content: I just tried it. It's working. More information from Agilent itself:http://www.home.agilent.com/agilent/editorial.jspx?ckey=1000001267:epsg:faq&id=1000001267:epsg:faq&nid=-11143.0.00&lc=fre&cc=FR

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 04, 2014, 07:17:41 pm
content: " and implementing the 10 mA range without the 100 mA range would require the long explanation, that you are currently reading."That's just funny

author: HighVoltage
author_rank: Super Contributor
timestamp: March 04, 2014, 10:29:50 pm
content: Very interesting,Are there any other hidden rages or menus in the Agilent 34401A?Thanks for this great information

author: Dr. Frank
author_rank: Super Contributor
timestamp: March 05, 2014, 07:24:31 am
content: Quote from: HighVoltage on March 04, 2014, 10:29:50 pmNope, that's the only one, also clear fron the description, that there is no other hardware inside to add features.That's also not that great of extension, as ACI is rarely used anyhow.I have poked the 34401A 10 years ago already, I think, and never used that additional range, afaik.Frank

author: Psi
author_rank: Super Contributor
timestamp: March 05, 2014, 07:56:16 am
content: it's hardly "Hidden" if Agilent themselves tell people about it

author: macboy
author_rank: Super Contributor
timestamp: March 05, 2014, 01:25:25 pm
content: I'd say it is definitely "hidden" (as in not normally accessible) but not "secret".If you think this is interesting, you may also be interested in an undocumented way to do offset-compensated 4-wire Ohms measurements...

author: Dr. Frank
author_rank: Super Contributor
timestamp: March 05, 2014, 03:07:02 pm
content: Quote from: macboy on March 05, 2014, 01:25:25 pmYou mean, with the 34401A, automatically, something like OCOMP ON, as the 3458A?Let's hear about that, that's really interesting..Frank

author: macboy
author_rank: Super Contributor
timestamp: March 05, 2014, 03:23:26 pm
content: Quote from: Dr. Frank on March 05, 2014, 03:07:02 pmAutomatic, sure, but not autonomous unfortunately. It requires a computer with GPIB or serial connection to the meter. The software will take a resistance measurement, then disable the current source (using more undocumented Pokes) and take another measurement, then calculate the difference. With the current source off, it is effectively measuring the thermoelectric voltage offset of the cabling since 'zero' current is flowing through the DUT, so there is 'zero' voltage to measure across it.You can find the code (in ... Basic!) in the examples directory after installing Agilent Intuilink for the 34401A. I don't imagine many people talk to their instruments in Basic these days, but the algorithm is simple and easily implemented in your platform of choice.

author: babysitter
author_rank: Frequent Contributor
timestamp: March 05, 2014, 08:18:31 pm
content: Call me interested in switching off the current source!

author: alex.forencich
author_rank: Frequent Contributor
timestamp: March 06, 2014, 07:36:02 am
content: Interesting. I installed the IntuiLink package in a VM and found the example files. Looks like it uses 4 different POKEs:DIAG:POKE -2,4281,0 with no particular comment, presuming 'close front end relay'DIAG:POKE -2,4281,4 with comment 'open front end relay'DIAG:POKE -2,3512,0 with comment 'force front end conf to change'DIAG:POKE 1,0,0 with comment 'force front end conf to be sent'Basically, the code works like this:put instrument in 2 wire ohms mode and send first pokeput instrument in 4 wire ohms modewaittake current source on measurementsend other 3 pokes to open relaywaittake current source off measurementsubtract

author: babysitter
author_rank: Frequent Contributor
timestamp: March 06, 2014, 08:21:12 am
content: Unrelated rant: Just called Agilent Service, I sent them a workplace 34401A for calibration on Feb 9th,ordered a calibration in their InfoLine service upfront, had a written order in the package and thought everything is well...Wrong. They send me a email with a quote asking for confirmation, which I answered on 26th.Still not enough, today i got: Received 02/12/2014. Awaiting quote approvalCalled, they skipped my mail but promised everything goes fine from today.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 24, 2022, 12:57:16 am
content: Just found an vb example of this from an intuilink installation fileIMPORTANT NOTE: This program describes an UNSUPPORTED CAPABILITY of theAgilent 34401 Multimeter. Agilent does not warrant or support theperformance or use of this feature in any manner.Some customers want to measure lower ACI than the 1 A range allows. Thelowest specified measurement on the 1 A range is 1% of range, or 10 mA(see footnote 4 in data sheet).The code below enables a hidden 10 mA ACI range.------------------------------------------------------------------------10 !20 !30 ! The following program makes several ACI readings using40 ! the undocumented 10 mA range.50 !60 ! The current range is enabled using the BUS and a DIAG:POKE 25,0,170 ! command. Once enabled, the range can be accessed over the80 ! BUS or from the front panel. You can still access the range90 ! even if power is cycled. To disable the range you need to100 ! to send a DIAG:POKE 25,0,0 command.110 !120 ! BCG 1/6/93130 !140 Nrdgs=10 ! NUMBER OF RDGS150 !160 ALLOCATE Rdgs(1:Nrdgs)170 !180 ASSIGN @Dvm TO 723190 !200 ! DIG OUT PREVIOUS ERRORS210 !220 CLEAR 7230 REPEAT240 OUTPUT @Dvm;"SYST:ERR?"250 ENTER @Dvm;A,A$260 PRINT A,A$270 UNTIL A=0280 PRINT "-----------------------------------------------------------"290 !300 ! SET UP 34401A310 !320 CLEAR @Dvm330 OUTPUT @Dvm;"*RST"340 WAIT .5350 !360 !370 OUTPUT @Dvm;"DIAG:POKE 25,0,1" ! Allows access to 10 mA380 OUTPUT @Dvm;"CONF:CURR:AC .01,MIN" ! ACI from the bus and390 OUTPUT @Dvm;"TRIG:COUN";Nrdgs ! front panel.400 OUTPUT @Dvm;"READ?"410 !420 FOR I=1 TO Nrdgs430 ENTER @Dvm USING "#,K";Rdgs(I)440 PRINT I,Rdgs(I)450 DISP I,Rdgs(I)460 NEXT I470 ! OUTPUT @Dvm;"DIAG:POKE 25,0,0" ! DISABLE 10 mA RANGE480 PRINT "-----------------------------------------------------------"490 END

author: Brandy
author_rank: Newbie
timestamp: January 05, 2023, 08:49:39 am
content: What is the advantage of the vb program compared to the poke mentioned from macboy in the first post?Btw, the "autorange" function is working upwards only. e.g. if you measure 10mA 1kHz and input a higher current value, the 34401 will change to the 1A range automatically (if you're in autorange mode). If you change from lets say 15mA/1kHz to 5mA/1kHz it will NOT switch to the 10mA range! This has to be done manually.