Home › Forums › Mooshimeter Support › Trouble reading 120V AC using Mooshimeter with custom Android APP
Tagged: VAC Custom App API
- This topic has 2 replies, 2 voices, and was last updated 5 years, 2 months ago by Anonymous.
Getting the Mooshimeter to read 60 Hz AC voltage correctly is a well-documented issue. The Mooshimeter needs to be set with a sampling rate of 4000 Hz and a sampling depth of 256 samples in order for the Mooshimeter to get enough data so that an RMS analysis yields the correct AC voltage.
With our custom Android App, then, we need to set the Mooshimeter up with these values:
SAMPLING:RATE = 4000 Hz (command code 9, byte = 5)
SAMPLING:DEPTH = 256 (command code 10, byte 3)
CH2:MAPPING = VOLTAGE (command code 30, byte = 0)
CH2:ANALYSIS = RMS (for AC) (command code 32, byte = 1)
When we do this, we read only ~87 VAC instead of the expected 120V AC. In a side-by-side comparison with our App vs. the Mooshimeter App, we get this:
125 Hz, 32 Samples: Our App=27 VAC, Moosh App=27 VAC
125 Hz, 256 Samples: Our App=12 VAC, Moosh App=27 VAC
500 Hz, 256 Samples: Our App=87 VAC, Moosh App=112 VAC
2000 Hz, 256 Samples: Our App=85 VAC, Moosh App=120 VAC
4000 Hz, 256 Samples: Our App=87 VAC, Moosh App=120 VAC
As you can see, when the Moosh App gets the sampling rate it needs, it gets 120 VAC, but our app can’t get more than 87 VAC. We must be missing some setting, but what the heck is it?
Thanks in advance for any help.
I think the issue is the range on the channel. The voltage channel has 2 available ranges – 60V and 600V. I think you’re in the 60V range and the channel is saturating, which is why you’re seeing the RMS peak out around 85V.
With your initialization commands, add
CH2:RANGE_I range 1 (code 31, byte 1, assuming 147xxx firmware)
D’oh! Yep, that was it. I thought range 0 was auto-range, but now I see that auto-range is an App setting, not a meter setting.