Stijn, Have you tried to power-cycle your counter?
May seem like a silly question, but just to make sure we are on the same page. I have had similar problems, but did not debug them all. I do remember that after writing the string successfully I had to power-cycle the counter thought, before it got accepted and past Calibration Lost message. When I did this I could not rule out that my programming to control the USB-GPIB infterface was correct, as I bone-headidly wrote my own from ground up. At the time all the stuff with GPIB was flimsy so that's why I just did not use what was available. Cheers, Magnus On 2020-11-11 11:46, Stijn wrote: > Hi All, > > I am one of the lucky persons with a PM6681 that has lost it's > calibration parameters. > > Unfortunatly it seems not as simple as sending: :SYST:UNPR; *PUD #261 > CALIBRATED: 2006-11-07, CALPLS: 4.25 ns, TMP: +22 °C > This produces an error. > If I sent: :SYST:UNPR; *PUD #253 CALIBRATED: 2006-11-07, CALPLS: 4.25 > ns, TMP: +22 °C > Then the counter accepts the string and stores it. > > BUT, I still get the Calibration Lost message. > > btw. the LF at the end of the string you receive from the counter is > added by the counter itself, so it does not count for the charactercount. > > I do have a different firmware version: PHILIPS, PM6681, 0, MAIN > V1.05 27 Jan 1997 / GPIB V1.13 27 Jan 1997 > > Stijn > > Op 09-11-2020 om 17:47 schreef Rex: >> Magnus and Azelio, >> >> (About Pendulum or Fluke or Philips PM6681 Counter or equivalent CNT-81) >> >> Here's a link to the thread where Magnus shared info in 2015. >> https://time-nuts.febo.narkive.com/6WTFfsyN/pm6680-or-53131a-for-timepod >> >> Your post is about half way down -- 2015-11-18 22:18:04 UTC >> >> Yesterday I dug out my GPIB-capable PC and sent a couple commands to >> my Fluke PM6681. >> >> First I tried a basic one: >> *IDN? >> and got >> PHILIPS, PM6681, 0, MAIN V1.09 26 JAN 2001 / GPIB V1.13 26 JAN 2001 >> >> So connection is good. Interestingly the *IDN command description >> says the PM6681 will return its SN but the SN field here is 0. Oh >> well, not important. >> >> Then I sent *PUD? >> and got >> #261 CALIBRATED: 2006-11-07, CALPLS: 4.25 ns, TMP: +22 °C[LF] >> where the [LF] at the end is not literal, it represents the line feed >> char 0x0a. >> >> So in addition to the CALPLS value, it looks like they also save the >> TMP in centigrade when the test was run. I wonder if the counter uses >> that? >> >> So I hope if my counter ever lost this cal value, I could send it >> this command: >> :SYST:UNPR; *PUD #261 CALIBRATED: 2006-11-07, CALPLS: 4.25 ns, TMP: >> +22 °C >> >> I don't plan to try that now. If it ain't broke don't fix it. >> >> There is one odd thing I see though. The last two of #261 is supposed >> to say the string length is 61. But it isn't. I count it as 53 chars. >> I don't know if this matters but the counter gave that number to me. >> In the Programming Manual description page for *PUD, it gives a >> couple examples and the #2nn values shown do have lengths that match >> their string lengths. >> >> If it is useful to anyone, I made a version of just the *PUD command >> description from the Programming Manual and put it here: >> www.xertech.net/pm6681/PUD_cmd.pdf >> >> I also made a version of the Interpolater calibration process page >> from the Service Manual. It can't really be used since it is obsolete >> and the old DOS program seems unobtanium. It may give a few hints >> what they were up to. >> I put it here: >> www.xertech.net/pm6681/interpolate_cal.pdf >> >> So thanks for pointing out that the *PUD command saved string is what >> you lose if the memory backup battery dies. Reading and saving the >> value is what I hoped for and now I've done it. >> >> If anyone has a PM6681 counter or equivalent with the "Cal.Lost" >> message, sending my string above might be good enough to get it >> working, though maybe not optimum. >> >> On 11/9/2020 1:58 AM, Magnus Danielson wrote: >>> Thanks for the memory refresh. >>> >>> You can read the string using PUD? >>> >>> Do that and keep the result. PUD and PUD? is the magic in the counter, >>> the rest is software and hardware outside of the counter for >>> calibration. >>> >>> In order to write, you need to move the calibration jumper inside. >>> >>> Cheers, >>> Magnus >>> >>> On 2020-11-08 23:01, Azelio Boriani wrote: >>>> Old story about the PM6681 (18 Nov 2015, thread: "PM6681 and Timelab") >>>> where a sort of calibration procedure is described: the PUD command is >>>> NOT a calibration command. >>>> PM6681 programming manual, page 9-127: PUD Protected User Data...This >>>> is a data area where the user may write ANY data up to 64 >>>> characters... >>>> If the user can write any data, how can it be a calibration command or >>>> calibration data area? >>>> Better watch out those 3V coin cells, we will never get the real >>>> calibration commands/procedure. I have tried with the disassembled >>>> firmware, no way. The visible strings of GPIB commands are all >>>> described in the programming manual, so nothing useful. >>>> >>>> On Sat, Nov 7, 2020 at 3:31 AM Magnus Danielson >>>> <[email protected]> wrote: >>>>> Hi Rex, >>>>> >>>>> I need to dig in the archive to refresh my memory. I don't recall >>>>> precisely, but I think I recalled that the manual indirectly >>>>> describes >>>>> the calibration data string. >>>>> >>>>> I have learned a few things from Pendulum, but I did not have the >>>>> right >>>>> tools at hand to set things up. >>>>> >>>>> There was a more recent setup that could use more modern >>>>> generators, but >>>>> the trick was still the same. You lock the generator and counter >>>>> to the >>>>> same frequency, then you set the generator to a small offset >>>>> frequency >>>>> from 10 MHz, which is 9.999 MHz as I recall it. This slowly sweeps >>>>> through all the phase-relationships between the reference >>>>> oscillator and >>>>> the counter input, thus sweeps the interpolator phase. It then >>>>> chooses >>>>> the calibration constant giving the lowest RMS error, as this is the >>>>> best compensation for the hardware min-point. All this is free from >>>>> memory. Then that value with calibration date is written into >>>>> memory. If >>>>> I recall correctly 2.21 ns is a typical value. >>>>> >>>>> I have PM6681 in need of calibration, and as I recall it I was >>>>> able to >>>>> program it enough for the calibration error warning did not show up. >>>>> This not to say it was actually calibrated. >>>>> >>>>> At some point I will return to that project. The generator I used did >>>>> not support that offset frequency, but I have others that do. >>>>> Also, my >>>>> crapiola GPIB programming needs attention. My intention is to >>>>> share the >>>>> fruits of this project when it comes to that. The lab has been in >>>>> shambles for too long, but shaping up slowly and nicely. >>>>> >>>>> Cheers, >>>>> Magnus >>>>> >>>>> On 2020-11-05 09:30, Rex wrote: >>>>>> Hi Magnus, >>>>>> >>>>>> Just catching up on list messages and saw this one from you. >>>>>> >>>>>> I have a Fluke PM 6881 counter. I don't think I've ever seen a >>>>>> description of a method for reading/restoring these battery >>>>>> backed up >>>>>> calibration constants. I looked for a way, as losing them is >>>>>> something >>>>>> I've worried about. Not that it has happened and I did replace the >>>>>> battery once. >>>>>> >>>>>> Is doing this described in one of the manuals? Sounds like it is >>>>>> through GPIB? I'd greatly appreciate any pointers to info or other >>>>>> details you might provide. >>>>>> >>>>>> I did see, in the service manual, a short description of a method >>>>>> for >>>>>> Interpolator calibration that seems to be for making these >>>>>> calibrations. Seems if the saved cal values get lost, the counter >>>>>> will >>>>>> display "CaL.LOSt". The cal procedure is driven by an old DOS >>>>>> program >>>>>> (that I've never found) and requires a: PM5768 Pulse gen, PM5193 LF >>>>>> Sig Gen, good 10 MHz, all GPIB controlled from the program. Never >>>>>> saw >>>>>> more details but sounds messy. If there is description of GPIB >>>>>> commands for reading/setting cal values, I missed them. >>>>>> >>>>>> thanks for mentioning this and anything more you can provide >>>>>> -Rex >>>>>> >>>>>> On 10/29/2020 5:37 PM, Magnus Danielson wrote: >>>>>>> Hi, >>>>>>> >>>>>>> I second this. You can read the calibration data out of the >>>>>>> counter and >>>>>>> save. I've done some experiments with that, but nothing >>>>>>> conclusive, but >>>>>>> I blame my lack of patience and not a proper setup. >>>>>>> >>>>>>> Do replace the battery, it is cheap and relatively easy to do. >>>>>>> >>>>>>> Would you loose this calibration, through a little GPIB commands >>>>>>> one can >>>>>>> write a fake value in. This will however not produce the best >>>>>>> resu. The >>>>>>> calibration routine actually runs an off beat frequency and then >>>>>>> test >>>>>>> different values, and look for least RMS value, because it is the >>>>>>> calibration point. I've not had time to replicate all that, but >>>>>>> I did >>>>>>> manage to write the fake value in and at one time get rid of the >>>>>>> CAL >>>>>>> LOST warning. >>>>>>> >>>>>>> Cheers, >>>>>>> Magnus >>>>>>> >>>>>>> On 2020-10-29 14:17, Azelio Boriani wrote: >>>>>>>> For those who have the PM6681 (aka CNT81): check the 3V memory >>>>>>>> backup >>>>>>>> cell and replace it before the dreaded calibration lost (CAL LOST) >>>>>>>> will appear on the LCD. Replace the coin cell with great care >>>>>>>> (with >>>>>>>> the counter powered up), see the service manual for the procedure. >>>>>>>> <https://archive.org/details/FLUKE_PM6681_Service_Manual> >>>>>>>> >>>>>>>> On Fri, Oct 23, 2020 at 6:17 PM Magnus Danielson >>>>>>>> <[email protected]> wrote: >>>>>>>>> Hi, >>>>>>>>> >>>>>>>>> On 2020-10-22 19:13, Attila Kinali wrote: >>>>>>>>>> On Thu, 22 Oct 2020 11:50:08 +0000 >>>>>>>>>> Giorgio Barinetti <[email protected]> wrote: >>>>>>>>>> >>>>>>>>>>> Choices are many, but I'll try to avoid the "older" machines >>>>>>>>>>> lile >>>>>>>>>>> 5370 or 5335. The 531xx series seems nice ( money apart ) >>>>>>>>>>> But again : which one between the 3 ? 53131, 53132 or 53181 ? >>>>>>>>>> Maybe try to get hold of one of the Philips (later licensed to >>>>>>>>>> Fluke) PM6680 or PM6681? These are more common in Europe than >>>>>>>>>> in the US, so the big US dominated websites/forums/.. don't >>>>>>>>>> mention them that often. Solid devices that can be had as low >>>>>>>>>> as 300€ if you are willing to wait, 500-800€ is the usual going >>>>>>>>>> price. The SR620 is the workhorse that drives a lot of the >>>>>>>>>> time and frequency metrology worldwide and can be had new and >>>>>>>>>> used (new on http://thinksrs.com goes for 800-2000€ used). >>>>>>>>>> >>>>>>>>>> If you go for a new one, I would consider looking at the >>>>>>>>>> Pendulum CNT-90 and CNT-91. (Pendulum is the company that >>>>>>>>>> took over Philips frequency counter business and the CNT-90 >>>>>>>>>> is the continuation of the PM668x line, also sold as PM6690 >>>>>>>>>> by Fluke) >>>>>>>>> Let me correct on the history and geniology there. >>>>>>>>> >>>>>>>>> Philips had a instrument making side called Philips Industrier >>>>>>>>> Järfälla >>>>>>>>> that did a range of measurement instruments. Later they joined >>>>>>>>> forces >>>>>>>>> with Fluke. Later Philips felt that the business unit was a >>>>>>>>> bad fit to >>>>>>>>> stay in Philips, so they sold it off to become a separate company >>>>>>>>> which >>>>>>>>> became Pendelum. Pendelum was really the business unit with >>>>>>>>> people etc >>>>>>>>> through that process, and the Fluke relation and rebranding >>>>>>>>> continued. >>>>>>>>> Naturally Pendelum moved out of the Philips Industrier >>>>>>>>> Järfälla office >>>>>>>>> over to Bälstabro (both locations in north of Stockholm) as it >>>>>>>>> was >>>>>>>>> sold >>>>>>>>> off. Pendelum also managed to rebrand their counters to >>>>>>>>> Tektronix, >>>>>>>>> which >>>>>>>>> mainly consisted of cosmetic changes to get the look and feel. >>>>>>>>> Pendelum >>>>>>>>> was operated for many years like this, some of their >>>>>>>>> production in >>>>>>>>> Pajala, where as other where done in Bälstabro. Later they >>>>>>>>> reshaped >>>>>>>>> the >>>>>>>>> production so that it moved to Poland where it remains. >>>>>>>>> Pendulum was >>>>>>>>> sold to Spectracom and was operated as a subsidary for a >>>>>>>>> while, until >>>>>>>>> they shut operation down. >>>>>>>>> >>>>>>>>> The CNT-80/81 (PM 6680 and PM6681) production went on as long >>>>>>>>> as they >>>>>>>>> had the timing ASIC. The CNT-90 (100 ps) was developed to the >>>>>>>>> CNT-91 (50 >>>>>>>>> ps), where the later replaced the CNT-81 (50 ps). They aimed >>>>>>>>> to do the >>>>>>>>> CNT-92, but could not at that time do it with the same technical >>>>>>>>> setup. >>>>>>>>> They also had the Wander Meter WM-10 which aided in testing >>>>>>>>> telecom >>>>>>>>> sync. After some testing, I suggested they would broaden the >>>>>>>>> product to >>>>>>>>> handle more signals and that is when they mostly firmware >>>>>>>>> upgraded >>>>>>>>> it to >>>>>>>>> the WM-11, and first time I tested the WM-11 the second '1' >>>>>>>>> was cut >>>>>>>>> out >>>>>>>>> from another '10' print and put over the '0'. Also, it was >>>>>>>>> still under >>>>>>>>> development. Several years later they where still going back >>>>>>>>> to my >>>>>>>>> list >>>>>>>>> of feedback. They later did a revamped this into a new >>>>>>>>> instrument with >>>>>>>>> even improved capabilities such as interfaces boards. This was >>>>>>>>> later >>>>>>>>> sold off to Calnex which sells it as Sentinel, which is a great >>>>>>>>> product >>>>>>>>> for telecom operators. >>>>>>>>> >>>>>>>>> I still have contact with some of the Philips/Fluke/Pendelum >>>>>>>>> staff and >>>>>>>>> owner. >>>>>>>>> >>>>>>>>> Cheers, >>>>>>>>> Magnus >>>>>>>>> >>>>>>>>> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
