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M77N - Mezzanine Card with 4 UARTs


The M77N is an M-Module with 4 high-performance RS232 or RS422/485 ports. It is designed as a replacement for M77 for automation, medical or in-vehicle applications in combination with MEN F12, F18 and A203.

Download data sheet

  • M77N Product ImageM77N Quad RS232/RS422/RS485 UART
  • M77N Product Image

Main Features

  • 4 high-performance UARTs
  • Compatible to 16550 UART
  • 128 bytes FIFO buffer
  • Serial data rates up to 2 Mbit/s
  • Software programmable 
  • Full and half duplex on 4 channels
  • 500 V AC optical isolation
  • -40 °C to +85 °C
M77N Product Image

Technical Data

  • Four independent full-duplex asynchronous high-performance UART channels
  • Four isolated groups, optical isolation
  • Software-configurable as RS232/RS422/RS485
  • 128-byte FIFO for each transmitter and receiver
  • UARTs fully software compatible with industry standard 16C55x type UARTs
  • Data rates up to 2 Mbit/s
  • Automated in-band flow control using programmable Xon/Xoff characters, in both directions
  • 5-, 6-, 7-, 8- and 9-bits data framing
  • Independent channel reset by software
  • Transmitter and receiver can be disabled
  • Serial
    • 4x RS232/RS422/RS485, isolated, D-Sub, 25-pin, receptacle
    • 4x RS232/RS422/RS485, isolated, board to board
  • M-Module
    • 1x A08/D08/INTA/IDENT, board to board
Product Standard
M-Module: ANSI/VITA 12-1997 (S2012)
Electrical Specifications
  • Supply voltage: +5 V (-3 % / +5 %)
  • Power consumption: 4.5 W max.
  • Isolation voltage: 500 V AC
Mechanical Specifications
  • Dimensions: M-Module: (W) 149 mm, (D) 53 mm
  • Weight: 78 g
  • Cooling: Air cooling, forced convection, airflow 1.0 m/s
Environmental Specifications
  • Operating temperature: -40 °C to +85 °C (EN 50155:2007, class TX, board)
  • Storage temperature: -40 °C (EN 60068-2-1:2007, Ab) to +85 °C (EN 60068-2-2:2007, Bb)
  • Humidity
    • EN 60068-2-30
    • EN 50155
  • Altitude: -300 m to +3000 m
  • Shock: EN 50155 (12.2.11)
  • Vibration: EN 50155 (12.2.11)
MTBF: 1 360 992 h @ 40 °C according to IEC/TR 62380 (RDF 2000)
  • Electrical safety: EN 62368-1 (former EN 60950-1) class II equipment
  • Flammability (PCBs): UL 94 V-0
  • EN 55022 class B (emission)
  • EN 50121-3-2 class B (emission)
  • EN 55024 class A (immunity)
  • EN 50121-3-2 class A (immunity)
Software Support
  • Linux
  • VxWorks
  • QNX
  • For more information on supported operating system versions and drivers see Software.

Ordering Information

Standard M77N Models

4 channels RS232/RS485/RS422, optically isolated UART, -40 °C to +85 °C

Miscellaneous Accessories

M-Module cable, 2 m, with 25-pin D-Sub plug/housing to pig tail


25 mounting screw sets to fix M-Modules on carrier boards (3 different screw types, 50 pieces each)



MDIS5 System (and Device Driver) Package (MEN) for Linux. This software package includes most standard device drivers available from MEN.


Linux TTY driver (MEN) for UART M-Modules, source code


MDIS5 System (and Device Driver) Package (MEN) for VxWorks. This software package includes most standard device drivers available from MEN.


VxWorks driver (MEN) for UART M-Modules, source code


MDIS4 system (and device driver) package (MEN) for QNX, source code. This software package includes most standard device drivers available from MEN.


QNX native driver (MEN) for UART M-Modules

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