BENNING MM 12

BENNING MM 12

Status	in progress
Source code	serial-dmm
Counts	40000
IEC 61010-1	CAT III (1000V) / CAT IV (600V)
Connectivity	Infrared (USB), Bluetooth LE
Measurements	voltage, current, frequency, duty cycle, resistance, continuity, conductance, diode, capacitance, temperature
Features	autorange, data hold, min/max/avg, crest, backlight, true-rms, dBm, dB, peak hold
Website	benning.de

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.

A driver supporting these devices including the MM 12 has been created and will be included in mainline sigrok once it passes acception (more details in pull request #99).

Hardware

• ADC: CYRUSTEK ES51966

Photos and Teardown

• 

  MM 12 connected to SmuView visualizing readings from the power grid

• 

  Front view

• 

  Measuring voltage and frequency from the power grid

• 

  Display, automatic backlight on

• 

  Protective sleeve removed

• 

  Rear

• 

  Optical data port (USB/Serial)

• 

  Included data cable (APPA IC-300U)

• 

  Batteries and fuses

• 

  Teardown 1/14

• 

  Teardown 2/14

• 

  Teardown 3/14

• 

  Teardown 4/14

• 

  Teardown 5/14

• 

  Teardown 6/14

• 

  Teardown 7/14

• 

  Teardown 8/14

• 

  Teardown 9/14

• 

  Teardown 10/14

• 

  Teardown 11/14

• 

  Teardown 12/14

• 

  Teardown 13/14

• 

  Teardown 14/14

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.

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 89.5 hours while providing data over Bluetooth LE.

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 capacity of the charger: ~2600mAh/cell

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.

Serial/USB

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-b/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-b/18-7A-93-BF-47-62

Scan for MM 12 with BLE connection:

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

Show readings from connected meter:

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

Open in SmuView:

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

Protocol

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

Resources

• BENNING MM 12 Product Website