M47 - Mezzanine Card with SSI Controller

The mezzanine card M47 is a Serial Synchronous Interface M-Module for connection of up to four sensors to optically isolated SSI outputs. Serial synchronous interfaces are commonly used for many kinds of sensors such as rotary encoders. Connection to thesensors is made by two signals - a transmit clock and a receive data signal.

All communication and signal decoding is done in an FPGA. Gray and binary decoding, the baud rate and word length are programmable for every single channel. The current value can be read from the DPR at any time.

In addition, the M47 features line-break detection.

The M47 is based on the M-Module ANSI mezzanine standard. It can be used as an I/O extension in any type of bus system, i.e. CPCI, VME or on any type of stand-alone SBC. Appropriate M-Module carrier cards in 3U, 6U and other formats are available from MEN or other manufacturers.


  • 4-channel 32-bit SSI
  • Serial Synchronous Interface
  • RS422A interface
  • Automatic communication
  • RAM-like double buffer user interface
  • Gray/binary decoding for each channel
  • Line-break detection
  • Absolute value data input
  • External Baud rate possible
  • Optical isolation for each channel
  • -40 °C to +85 °C versions


SSI Interface
  • 4-channel Serial Synchronous Interface (SSI)
  • Optical isolation
  • RS422A interface
Data Transmission
  • Baud rate
    • 62.5 kbaud, 125 kbaud, 250 kbaud, 500 kbaud
    • Programmable for each channel
  • Word length
    • 1..32 bits
    • Programmable for each channel
16-byte RAM-like double buffer user interface
  • 4 RS422 ports, optically isolated
  • Supply voltage for external sensors etc.: 5V (±10%), 400mA max. all channels summed up
  • Automatic communication
  • Gray and binary decoding, programmable for each channel
  • Sensor connection detection
  • Interrupt triggering on a new data transmission
Peripheral Connections
  • Via front panel on a shielded 25-pin D-Sub receptacle connector
  • Via carrier board (rear I/O)
M-Module Characteristics
Electrical Specifications
  • Isolation voltage
    • 500V DC between M-Module interface and external sensor interface
    • Voltage between the connector shield and sensor interface is limited to 180V using a varistor; AC coupling between connector shield and sensor interface through 10nF capacitor
  • Supply voltage/power consumption: +5V (4.85V..5.25V), 150mA without external sensors connected, max. 850mA with 4 sensors connected
  • MTBF: 33,000h @ 50°C (derived from MIL-HDBK-217F)
Mechanical Specifications
  • Dimensions: conforming to M-Module Standard
  • Weight: 60g
Environmental Specifications
  • Temperature range (operation):
    • 0..+60°C or -40..+85°C
    • Airflow: min. 10m³/h
  • Temperature range (storage): -40..+85°C
  • Relative humidity range (operation): max. 95% non-condensing
  • Relative humidity range (storage): max. 95% non-condensing
  • Altitude: -300m to + 3,000m
  • Shock: 15g/11ms
  • Bump: 10g/16ms
  • Vibration (sinusoidal): 2g/10..150Hz
  • Conformal coating on request
PCB manufactured with a flammability rating of 94V-0 by UL recognized manufacturers
Tested according to EN 55022 (radio disturbance), IEC 61000-4-2 (ESD) and IEC 61000-4-4 (burst)
Software Support