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Brymen BM857

Brymen BM857

Brymen BM857
Status supported
Source code serial-dmm
Counts 50000, 500000(DCV), 999999(Hz)
IEC 61010-1 CAT III (1000V) / CAT IV (600V)
Connectivity RS232
Measurements voltage, frequency, diode, resistance, continuity, capacitance, current
Features autorange, data hold, crest, backlight, true-rms, dBm (selectable impedance), %4-20mA
Website brymen.com BM857s BM859s

The Brymen BM857 is a 50000 counts (500000 DC V), CAT III (1000V) / CAT IV (600V) handheld digital multimeter with RS232 connectivity. The BM859s is also supported, it uses the same protocol. Adapter kits ship with IR to RS232 cables, and include RS232 to USB converters.

Higher end models support dual temperature sensors and difference mode, and the reference impedance for dBm measurements can be chosen in a range between 4 and 1200 Ohms.

Hardware

Multimeter:

  • Multimeter IC: TBD
  • Precision +2.5V Voltage reference: Analog Devices REF43
  • True RMS-to-DC converter: Analog Devices AD737
  • EEPROM(?): Chip marked S24C0.
  • Unidentified: Several 062-JRC chips. These appear to be JFET opamps.
  • Unidentified: Two QFP64 chips.
  • TODO

Cable:

Photos

Bm859s Front Bm859s Front

Bm857 Mcu 2blcdc Bm857 Mcu 2blcdc

Bm857 Cable Clips Bm857 Cable Clips

Brymen Br85x Dmm Hookup Side Brymen Br85x Dmm Hookup Side

Bm857 Cover Front Bm857 Cover Front

Brymen Br85x Dmm Hookup Angle Brymen Br85x Dmm Hookup Angle

Bm857 Upperpcb Top Bm857 Upperpcb Top

Bm857 Upperpcb Bottom Bm857 Upperpcb Bottom

Bm857 Front Noholster Bm857 Front Noholster

Bm857 Lowerpcb Top Bm857 Lowerpcb Top

Bm857 Lcdc Bm857 Lcdc

Bm857 Ics 2 Bm857 Ics 2

Bm857 Box Left Bm857 Box Left

Bm857 Cover Back Bm857 Cover Back

Bm857 Back Bm857 Back

Bm857 Inside Backside Bm857 Inside Backside

Bm 857 Mugshot 500000 Bm 857 Mugshot 500000

Bm857 Hv Slots Bm857 Hv Slots

Bm857 Input Circuit Bm857 Input Circuit

Bm857 Mcu 2blcdc 2 Bm857 Mcu 2blcdc 2

Bm859s Display Segments Bm859s Display Segments

Bm857 Back Noholster Bm857 Back Noholster

Bm857 Lcd Backlit Bm857 Lcd Backlit

Bm857 Package Contents Bm857 Package Contents

Bm859s Box Front Bm859s Box Front

Bm859s Manual Bm859s Manual

Bm857 Opened Bm857 Opened

Bm857 Lowerpcb Bottom Bm857 Lowerpcb Bottom

Bm857 Hv Walls Bm857 Hv Walls

Brymen Br85x Dmm Hookup All Brymen Br85x Dmm Hookup All

Bm859s Front Sleeve Bm859s Front Sleeve

Bm857 Ics Bm857 Ics

Brymen Br85x Dmm Hookup Top Brymen Br85x Dmm Hookup Top

BM850s series

The BM857s and BM859s meters (the BM850s series) uses the same protocol and works with the BC-85Xa adapters.

    - 
        [](./img/Bm859s-front-sleeve.png)

BM859s front with sleeve

    - 
        [](./img/Bm859s-front.png)

BM859s front

    - 
        [](./img/Bm859s-manual.png)

BM859s manual

    - 
        [](./img/Bm859s-box-front.png)

BM859s box front

    - 
        [](./img/Bm859s-display-segments.png)

BM859s display segments

Protocol

Serial communication (genuine COM port), textual presentation of measurement values (floating point, normalized mantissa plus exponent), combined with binary bit fields for current meter's function and thus measured unit, variable length records with control chars in the header/footer (DLE, STX/ETX) around the mode flags and value's text, up to 22 bytes per DMM packet. See resources below for a full description of the protocol.

Resources- vendor's BM810/BM830/BM850 page which links to individual 857/859 devices