Logging Handheld Multimeter data point limits and request for options - Page 1
Forum section: electronics / testgear

author: gwu
author_rank: Contributor
timestamp: December 30, 2020, 06:08:39 am
content: I have a Fluke 289 and have been using its record/logging feature to diagnose faults on some equipment. I never paid too much attention to Fluke's recording limits but I finally hit a limitation. When I set my sample interval to be 1sec the Fluke will only record for 2 hours and 47 min. Thus the 10000 sample limit on data logging size. What I find odd about this is that the 10000 sample limit does not fill the whole memory, rather its a single recording limit. The 2hr47min may seem long enough, and it has been in the past, thus I never paid too much attention to it. Yet, that limit proved to be annoying in logging over night. Events occurred after the 2hr47min mark, and I didn't have a record of them. I don't want to be waking up multiple times in the middle of the night to re-start the logging. So now I need a different solution to my logging needs.What's out there that is handheld and can keep logging for 6hrs+? Ideally, without a secondary device like a computer or phone, etc.Alternatively, whats handheld that will record to something small and battery powered? I am ruling out AC power from the logging system. Having a spare cheap phone around to run software may be an option if its the only way I can log over night.Having something like arduino power by battery, connected to the DMM via a USB cable, may be ok but I would prefer not to do that. If I was to go down that path can I do that with the FLuke 289?What I can see from the multimeter spreadsheet that I can recognise at the moment is a Unit-T181A and Brymen BM525. I would prefer to avoid Uni-T UT181A as my experience with Unit-T is subpar and it just falls short of 6hrs with 20000 samples... The Brymen BM525 may be an option but I am wondering if there is something else that is feasible and not as expensive as Gossen.I don't want to spend as much as I did on Fluke 289 as there is nothing else that I really dislike about it for my needs (I am not concerned about the size, the screen readability or the time it takes to turn on). I am not looking to move it on. I had a quick look online at Keysight but I am struggling to understand their sample limits, and what I can record to the DMM itself vs externally. I am in Australia but happy to source equipment from elsewhere: my Brymen 867s is from Germany (used so I can do voltage and current measurements at the same time).I appreciate the suggestions on viable options for a stand alone DMM without AC (preferred) or a DMM+device without AC.Cheers.

author: bdunham7
author_rank: Super Contributor
timestamp: December 30, 2020, 06:18:03 am
content: Is your recording threshold set to 0%? Does it need to be?

author: gwu
author_rank: Contributor
timestamp: December 30, 2020, 06:28:39 am
content: I can't see how I can change the recording threshold on 289. But no, right now I need to see deviations from an expected value. Maybe I'll have a need to record everything in the future but I don't right now.

author: bdunham7
author_rank: Super Contributor
timestamp: December 30, 2020, 06:41:48 am
content: Go into SETUP, then RECORDING and you should see options for event thresholds for AUTOHOLD and RECORDING. The default is 4%. If you have any setting other than 0%, the meter will only record a data point if there is a change of more than that amount from the previous reading. If you are monitoring something that changes slowly or occasionally, then the meter will check every second (if you have selected 1 second as the interval) but only record a data point if there is a change of more than the threshold. You can also select an interval of more than 1 second and this can be done automatically by setting it to 1 second first, then going up to recording time and entering the length of time you want to record. The interval will be adjusted to make sure that there is enough data points for that time.Now that I think about it, I'm not sure the threshold change will actually let it record longer, but only saves some memory. The interval change will let it record proportionally longer. You'll have to try it or read the manual and see if it clarifies that.

author: gwu
author_rank: Contributor
timestamp: December 30, 2020, 09:33:54 am
content: I had a read of the manual and here is what it says:"There are two measurement record types that are captured during a recording session: interval and event. An interval record covers a user-specified interval. An event record has a duration determined by the activity of the measured signal and can interrupt an interval record. Even if an interval record is interrupted, a record will end and a new interval record will begin when the scheduled interval time expires. Event records are triggered by the measured signal varying more than an adjustable percentage of the value measured at the start of the record. This adjustable percent is called the Event Threshold for recording.A record ends when one of the following occurs:•The start of a new interval record.•A range overload, causing the Meter to change range.•A non-ranging overload, when in manual range or the highest range.•The measured value changes more than 4 % of the measured value at the start of the record.•The recording session terminates.A recording session termination can be caused by one of the following:•Recording session duration expiring.•Manually stopping the recording sessionNoteThe maximum number of recorded sample intervals is 10,000. The maximum number of recorded events is 15,000 minus the number of sample intervals. These maximum numbers are proportionally decreased when the available memory is low. "If I am reading that right then I can increase my interval from 1s to something higher to give me a longer duration of recording. In the meantime if an event occurs (when signal is outside of the set threshold percentage of initial level at the start of recording) there will be an interrupt and the event will be recorded. That may do the trick! I'll need to give it a go and see. There is still the 10000 samples or 15000 events minus samples. I'll see how I go with this.In the meantime, what other handheld DMM options are out there?

author: HKJ
author_rank: Super Contributor
timestamp: December 30, 2020, 10:45:53 am
content: You can always check Brymen. BM525 is 87000 points or half that when using dual display.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 30, 2020, 02:12:01 pm
content: Did Dave/UEI ever work out all the problems with the 121GW? I've done some fairly long data logs with that meter recording to the internal card but it had firmware problems.You also had to remove the card to pull the data. I cracked one of the card holders. Still, may be an option depending on the other requirements.Not sure what Fluke charges for the cable and software.

author: gwu
author_rank: Contributor
timestamp: December 30, 2020, 03:01:00 pm
content: Quote from: joeqsmith on December 30, 2020, 02:12:01 pmI did have a look at the 121GW. The idea of a card to store data really appealed. The forum thread on 121GW indicates that there are still issues.My original Fluke purchase was a pack of DMM with the cable and software so I am ok on connecting it to a PC. Unfortunately I still need to leave the DMM away from an AC to do the recording.