PSTN V.92 Modem
Wall mountable PSTN modem with wide range 85 - 264 Vac power supply in sealable housing. Isolated 3-wire RS-232 and 3-wire RS-485 interfaces with RJ45 connectors, allowing easy installation. Meant for 'heavy' industrial environments: the Indubox PSTN III is approved according to extended electromagnetical immunity requirements in the electricity market in Belgium (Laborelec, TST 25-3).


  • Industrial PSTN modem for metering applications
  • RS-485 interface
  • Watchdog reset
  • 'Heavy Duty' certification


  • Housing:
    Wall mountable PSTN modem in sealable housing
    IP51 Bausch InduBox bottom enclosure and sealable connector cover (with sealing screw): ABS with self-extinguishing V0 additive transparant, sealable cover: polycarbonate with self-extinguishing V1 additive
    Overall dimensions with connector cover: 180 mm x 108 mm x 71 mm
    Overall dimensions without connector cover: 145 mm x 108 mm x 71 mm
  • Power Supply:
    Universal integrated 85-264 Vac 50/60 Hz power supply (optional: 10-60 Vdc)
    Power consumption: Pidle = 1.8 W / Pmax = 2.0 W
  • Engine:
    Based on Silicon Labs Isomodem solution
    Hardware and software flow control and speedbuffering
    Type I and Type II Caller ID detect 
    Call progress,blacklisting
    Integrated DAA
    Globally compliant line interface
    Extension pickup detection
    Digital Line protection
    Line –in-Use detection
    Low power consumption TBD
  • Communication protocols:
    ITU-T V.92 
    V.90,V.34,V.32bis, V.32, V.22bis 
    V.21,Bell 212A, Bell103
    V.23 Reversing,V.23 half-duplex
    V.29 FastPOS and V22bis fast connect
    V.80 Synchronous Access Mode
    V.44,V.42bis, MNP5 data compression 
    Error Correction: ITU-V.42
    Call Waiting detection 
  • Interface & Connectors:
    One complete non-isolated serial RS-232 configuration interface 
    - TxD, RxD, DCD, DTR, RTS, CTS, RI and GND / RJ-45 connector
    DTE Interfaces:
    3-wire serial RS-232 (RXD, TxD, GND') & '+V' connection - Galvanically separated
    3-wire serial RS-485 (A, B, GND') & '+V' connection - Galvanically separated
    RJ-11 telephone line connector
    2-pin removable terminal block with screw contacts for Mains 
  • Reset: Long term watchdog cicuit (seperate Atmel micro-controller) 2 possible ways to reset the modem: - Configurable, periodical reset (each 1 to 168 hours) - External reset triggered by the '+V'-connection (5-25V) with the meter in the RS-232 and RS-485 interfaces: disconnection of power supply during 20 seconds when a negative slope (5-25V to 0V) is detected on the '+V'-input. ( the '+V'-connection can also be used for powering (100 mA Imax) an external device (+5V' out)
  • Environmental: - 25°C / + 55°C: temperature in use 10% - 75%: humidity in use (non condensing)
  • Certification: Approvals Indubox PSTN III:
    Standard CE / EMC
    TST25-3 (additional extended immunity tests)  ‘modems bestemd voor teleopname van metingen'

Additional Info

The InduBox PSTN III modem is especially conceived for 'heavy' industrial environments: the modem is tested and approved according to the TST 25-3 extended immunity requirements in the Belgian electricity market. When testing EN61000-4-3 - electromagnetical compatibility - Laborelec, the official Belgian lab creates a test environment which generates 30 V/m field strengths instead of the standard 'normal' field strength of 10 V/m (CISPR24 level = 10 V/m).
The modem has an integrated 85-264 Vac power supply circuit with a low power consumption (Pidle = 1.8 W / Pmax = 2.0 W).
Built in a double sealable IP51 housing with transparent lid the modem comes with two different and parallel usuable isolated serial interfaces, one RS-232 (3-wire), one RS-485 (3-wire).
An important industrial feature is the long term, configurable watchdog (seperate Atmel microprocessor).
This long term watchdog has 2 possible ways to reset the modem :
1. Configurable and periodical 'hard' reset (each 1 to 68 hours).
2. External 'hard' reset triggered by the '+V'-connection with the meter on pin 1 of RS-232 and/or RS-485 (JP4 and/or 5 on 'Meter' position) : the power supply of the InduBox modem will be disconnected during 20 seconds when a negative slope (5-25V to 0V) is detected on the '+V'-input.

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