UNI-T UT612
The UNI-T ut612 LCR Meter Dual Display comes with an USB interface that encapsulates standard serial over USB/HID. The main chipset inside the device responsible for the meassurements is the Cyrustek ES51919, the serial output from this chip is sent to a Silicon Labs CP2110 HID USB to UART Bridge.
Protocol ES51919
The protocol for the es51919 was reverse engineered as part of the DER-EE 5000 driver that uses the same chipset. Below is the excerpt from the source code.
Public official documentation does not contain the protocol description, so this is all based on reverse engineering.
Packet structure (17 bytes):
0x00: header1 ?? (0x00) 0x01: header2 ?? (0x0d)
0x02: flags
bit 0 = hold enabled
bit 1 = reference shown (in delta mode)
bit 2 = delta mode
bit 3 = calibration mode
bit 4 = sorting mode
bit 5 = LCR mode
bit 6 = auto mode
bit 7 = parallel measurement (vs. serial)
0x03: config
bit 0-4 = ??? (0x10)
bit 5-7 = test frequency
0 = 100 Hz
1 = 120 Hz
2 = 1 kHz
3 = 10 kHz
4 = 100 kHz
5 = 0 Hz (DC)
0x04: tolerance (sorting mode)
0 = not set
3 = +-0.25%
4 = +-0.5%
5 = +-1%
6 = +-2%
7 = +-5%
8 = +-10%
9 = +-20%
10 = -20+80%
0x05-0x09: primary measurement
0x05: measured quantity
1 = inductance
2 = capacitance
3 = resistance
4 = DC resistance
0x06: measurement MSB (0x4e20 = 20000 = outside limits)
0x07: measurement LSB
0x08: measurement info
bit 0-2 = decimal point multiplier (10^-val)
bit 3-7 = unit
0 = no unit
1 = Ohm
2 = kOhm
3 = MOhm
5 = uH
6 = mH
7 = H
8 = kH
9 = pF
10 = nF
11 = uF
12 = mF
13 = %
14 = degree
0x09: measurement status
bit 0-3 = status
0 = normal (measurement shown)
1 = blank (nothing shown)
2 = lines ("----")
3 = outside limits ("OL")
7 = pass ("PASS")
8 = fail ("FAIL")
9 = open ("OPEn")
10 = shorted ("Srt")
bit 4-6 = ??? (maybe part of same field with 0-3)
bit 7 = ??? (some independent flag)
0x0a-0x0e: secondary measurement
0x0a: measured quantity
0 = none
1 = dissipation factor
2 = quality factor
3 = parallel AC resistance / ESR
4 = phase angle
0x0b-0x0e: like primary measurement
0x0f: footer1 (0x0d)
0x10: footer2 (0x0a)