Products > Test Equipment
OWON XDM1041 the unknown multimeter...
BugCatcher:
UniSoft
You are right! Data must be in Flash. Leakage of SRAM (deep sleep) is above 100uA.
BTW: Could it be that D1 (in front of battery) is in wrong direction?
UniSoft:
--- Quote from: BugCatcher on January 09, 2022, 09:11:03 am ---You are right! Data must be in Flash.
--- End quote ---
I saw it in the firmware code.
--- Quote from: BugCatcher on January 09, 2022, 09:11:03 am ---BTW: Could it be that D1 (in front of battery) is in wrong direction?
--- End quote ---
Yes, for sure... I made a mistake.
By the way, Does anyone know what the TFT display is used there.
I did not find anything with such a pinout.
PB2 - D/C (0: Command; 1: Data)
PB10 - CLK
PB1 - Probably RESET
BugCatcher:
Next Story: Sampling Rate
The data sheet promises up to 65Hz sampling rate (15.4ms)
First step:
timing only
I started with the DMMEasyControl tool
- simple measurement due to time stamps in download,
1000 samples per run (DCV, 5V fixed, fast mode)
set sampling rate (ms) measured sampling rate (ms)
16 51.1
18 51.1
20 48.0
25 50.6
30 51.2
40 52.2
50 77.9
100 110.1
1000 1007.8
-> Dramatic overhead for sampling rates below 1s!
-> Time stamps are heavily impacted by jitter (a few 10ms)
Next test is XDM with internal recording
Due to missing time stamps only total time for 1000 samples (hand stopped)
15ms -> 15s
30ms -> 30s
100ms -> 100s
-> Internal recording of XDM looks ok!
Next step:
What about the quality of the stored measurements?
Used a function generator with a slow triangle wave (below 100mHz)
downloaded an internal recording of the XDM
(see "XDM_internal_recording)
-> looks ok! No Jitter!
Next test is DMME recording with 50ms samples. Big surprise ...
- samples are repeated!
- new sample value only after a few 100ms, heavily impacted by jitter!
(see "DMME_repetition_of_samples")
What happens for 1s sampling?
- no longer repeated samples
- impact of jitter still visible
(see "DMME_jitter_at_1s_sampling)
Potential explanation:
- rate for new sample values is similar to rate on PC-display (in the range of 2Hz)
- DMME SW is doing nasty things: delivering correct number of requested samples, update
of sample value only in sync with display of PC-screen
My conclusion:
-> for sample rates below 1s you have to use the internal recording!
Ringmodulator:
Check out the Voltcraft VC-655 BT
Looks like the same unit in a different dress....
https://asset.conrad.com/media10/add/160267/c1/-/en/002357060DS00/datenblatt-2357060-voltcraft-vc-655-bt-tisch-multimeter-digital-cat-i-1000-v-cat-ii-600-v-anzeige-counts-55000.pdf
Chris
Johnny B Good:
It appears to be the same breed of "Duck", you know, if it walks like a duck, quacks like a duck... ::)
At nearly 200 Euros (and possibly VAT on top - there didn't seem any point checking at that pricing level) for the Voltcraft version, I decided to spend my money on the Banggood offering, namely the OWON XDM1041 USB model for just £96.46 plus a little extra on shipping and tariff insurance (still just under the 99 quid mark with an estimated delivery by the 29th - a realistic estimate going by recent past experience).
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