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Benning MM 12 - 01 - Front Sleeve.png
Status in progress
Source code appa-dmm
Counts 40000
IEC 61010-1 CAT III (1000V) / CAT IV (600V)
Connectivity Infrared (USB/RS232), Bluetooth LE
Measurements voltage, frequency, period, resistance, continuity, diode, capacitance, current, temperature
Features autorange, data hold, auto hold, peak hold, min/max/avg, relative (%/delta), level (dB/dBm), automatic backlight, true-rms, data logging (40000 records), auto store (1000 records), auto-v/LoZ, ac+dc, VFD, secondary display value, auto fuse detector

The BENNING MM 12 is a 40000 counts, CAT IV (600V) / CAT III (1000V) dual display handheld digital multimeter with USB and Bluetooth LE connectivity.

It is based on the APPA 506B, See also: APPA Multimeters.

The driver supporting these APPA-based devices ("appa-dmm" in sigrok) has been created and will be included in mainline sigrok once it passes acception (see developement repository branch appa-dmm).


  • MCU: CYPRESS MB95F718E (1828 6TTL E2)
  • ADC IC: CYRUSTEK ES51966A (1839-GL9K)
  • LCD IC: HOLTEK HT1622 (B829J006QG2)
  • BLE SoC: AMICCOM A8105 (F5001AQ5A AMV38041 1932D)
  • EEPROM: 2 x Microchip 24LC512 (I/SM 1810UP4)
  • Fuses:
    • Current range 10A: Amp rating: 11A, Voltage rating: 1kV, Interrupting rating: 30kA, Opening: Fast acting, Size: 10mm x 38mm
    • Current range 400mA: Amp rating: 0.44A, Voltage rating: 1kV, Interrupting rating: 10kA, Opening: Fast acting, Size: 10mm x 34.9mm
  • Power supply: 4 x IEC LR6 1.5V (works fine with IEC HR6 1.2V)

Photos and Teardown

Review and Test

Unless noted otherweise, the tests in this section have been performed by Cymaphore on a Benning MM 12, Firmware v1.13

Usage of rechargable NiMH batteries

The device works quite well with rechargable batteries. Voltage boundaries are well selected to suit the needs of both Alkaline and NiMH cells. For NiMH the reported battery level is of course always too low.

Battery indication

  • FULL: >5.66 V (~ 1.415 V/cell)
  • HALF: >5.16 V (~ 1.290 V/cell)
  • LOW: >4.66 V (~ >1.165 V/cell)
  • WARN: >4.06 V (~1.015 V/cell)
  • Forced POWER-OFF: <4.06 V (~ 1.015 V/cell)

The cut-off voltage (device turns off with "Battery" error) of about 1V/cell is well suited for NiMH cells.

Current consumption

Test supply voltage: 4.8 V


Function Bare w. Backlight active w. BLE active w. Optical active (w. BLE standby)
AutoV / LoZ 16.3 mA 26.2 mA 21.9 mA 19.3 mA 18.7 mA
V~ 16.2 mA 25.8 mA 21.7 mA 18.7 mA 18.1 mA
mV~ 15.8 mA 25.6 mA 21.4 mA 18.6 mA 18.3 mA
V= 16.1 mA 25.8 mA 21.6 mA 18.8 mA 18.2 mA
mV= 15.8 mA 25.6 mA 21.8 mA 18.7 mA 18.1 mA
Ohm 16.4 mA 26.4 mA 22.4 mA 19.7 mA 18.5 mA
Capacity 19.6 mA 30.0 mA 25.0 mA 23.0 mA 21.5 mA
Diode 19.7 mA 30.0 mA 25.5 mA 23.2 mA 22.0 mA
A~ 16.0 mA 26.3 mA 22.5 mA 19.2 mA 18.6 mA
Temperature 16.9 mA 27.3 mA 25.0 mA 19.7 mA 19.6 mA
Average 16.9 mA 26.9 mA 22.9 mA 19.9 mA 19.2 mA
Maximum 19.7 mA 30.0 mA 25.5 mA 23.2 mA 22.0 mA
Minimum 15.8 mA 25.6 mA 21.4 mA 18.6 mA 18.1 mA

Average, Min, Max

Average of averages: 21.639 mA
Max of Maximums: 30.000 mA
Min of Minimums: 15.820 mA

Estimated consumption of individual features

Avg. backlight consumption: 9.780 mA
Avg. BLE active consumption: 5.580 mA
Avg. Serial active consumption: 2.780 mA
Avg. BLE standby consumption: 2.280 mA

Test of Battery duration performance

For this test, a long-duration logging situation was set up.

For the test I used NiMH cells that have only been used a couple of times before.

In this test the device was able to continously work for 89.3 hours while providing data over Bluetooth LE to a desktop client.

In comparison, the 50 hours of battery life on alkaline cells claimed in the 506B datasheet seem to be a pessimistic worst-case estimation.

Test parameters

  • Display light configured to be always off
  • Uninterrupted operation
  • Permanent Data acquisition over Bluetooth LE at maximum possible rate
  • AC Volt function
  • Continuous measurement of Voltage and Frequency of the power grid

NiMH-Cells used for the test

  • 4 x VARTA Endless 56686 (LSD)
  • Nominal capacity: 2500mAh
  • Fully charged before the test, reported charged capacity of the charger: ~2600mAh/cell (doesn't consider charging efficiency).

Test results

  • Test duration: 89 hours, 17 minutes, 40 seconds
  • End condition: Device shut down and reported "BATTERY"
  • Cell voltage after end of test: ~1.04 V/cell

Examples: Establish data connection between sigrok and MM 12

Important: Driver is not (yet) part of mainline sigrok - see this repository in github if you want to use it already.


Assuming the meter is turned on, plugged in and the usb-serial driver is loadad and up (should happen automatically). /dev/ttyUSB0 is used as an example.

List devices, if unsure what the serial port is:

 # sigrok-cli --list-serial
 /dev/ttyUSB0  CP2102 USB to UART Bridge Controller - 2020y000231

Scan for MM 12 with USB/Serial connection:

 $ sigrok-cli -d benning-dmm:conn=/dev/ttyUSB0 --scan

Show readings from connected meter:

 $ sigrok-cli -d benning-dmm:conn=/dev/ttyUSB0 --continuous

Open in SmuView:

 $ smuview --driver benning-dmm:conn=/dev/ttyUSB0

Bluetooth LE

Assuming the meter is turned on and bluetooth activated on the meter and the PC. Important: Your Bluetooth-Controller must support BLE.

Scan for BLE devices:

 # sudo sigrok-cli --list-serial
 bt/appa-dmm/18-7A-93-BF-47-62   BENNING MM12 (BLE)

If your OS / UI supports it, you can also use the Bluetooth scanning capability from the system tray and pick the MAC address from the details there.

"18:7A:93:BF:47:62" acts as an example for the device address you will find. For sigrok the ":" must be replaced by "-" for now. That device address is used for the following examples, just replace it by the address of your own meter.

The full connection string then would look like this, as seen in the scanning result: bt/appa-dmm/18-7A-93-BF-47-62

Scan for MM 12 with BLE connection:

 $ sigrok-cli -d benning-dmm:conn=bt/appa-dmm/18-7A-93-BF-47-62 --scan

Show readings from connected meter:

 $ sigrok-cli -d benning-dmm:conn=bt/appa-dmm/18-7A-93-BF-47-62 --continuous

Open in SmuView:

 $ smuview --driver benning-dmm:conn=bt/appa-dmm/18-7A-93-BF-47-62


The protocol on Serial and BLE is the same like for most of the APPA based models.