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Single Section Digital Axle Counter "SSDAC-G36" Versatile axle counting system configurable as 2DP, 3DP, 3DP-2S(IBS), AS


G36 is a fail-safe 2/2 microcontroller based axle counting system for section proving in Railways. G36 can be configured to various versions using fool-proof method thus prevents wrong configuration at site, ensures highest degree of safety. Operating mode like preparatory, clear and occupied, configuration status, wheel counts and error messages are constantly displayed on the system LCD status panel and interactive Reset box.

Magnetic sensors detects the axle counts and direction of train movements that is transmitted to the other end of the system to verify and clear the block. Wheel sensed at one DP will cleared at any DP. The section status can be fed directly to further controlling systems through vital relay contacts. Each section has two or three detection points based on configurations. System unit is housed near the track with its DP placed at a variable distance of 15 Mts.

Reliable communication between systems with a cable loss of 30dB using V.23 FSK modem at 1200bps, assured by CRC check with redundant messages. Fixed pair communication along with interlocked addressing between units ensures fail-safety. Built-in event logger logs normal and error data that can be downloaded on to a PC using RS232 serial port. Additional FSK modem available in event logger card connected to interactive Rest Box at station (requires extra pair in quad cable). User-friendly GUI aids to print reports.

G36 works on 24 VDC power supply, integrated with lightening surge protectors.

Stable operation at adverse environmental conditions from –10°C to 70°C. Reliable train detection by sensors exposed to water clogging due to heavy rains.

SSDAC- G36 Unit

SSDAC- G36 Reset Box

SSDAC- G36 Relay Unit

Web Mounted Tx Rx Coil



  • Microprocessor based fail-safe embedded system
  • Detection of axles and direction of train movement
  • Fixed pair communication, CRC check & unique addressing of units ensures fail-safety
  • User friendly GUI aids to download events via RS232 port
  • Units are housed in location boxes near the tracks

Axle Detectors

  • Web mounted on track, works with 90-R, 52Kg, 60Kg rails
  • Phase detection principle employed
  • Signals fed at 21Khz and 25Khz to Tx coils at 60V RMS
  • Axles above 550mm are detected

Reset Box

  • Amended as per RDSO Ver 2.0 Specification
  • Interactive RESET Box with LCD for live status display of DP Status (2DP, 3DP, 3DP-2S, AS)
  • Section Status (Wait for Reset/Preparatory, Section Occupied / Clear)
  • Wheel Counts (Local and Remote DP)

Technical Specifications

  • Complies to RDSO/SPN/177/2005 Ver 2.0 with amendment 1
  • IV&V of system software meets stringent CENELEC 50128, SIL-4
  • Mature and rugged with inherent fail-safety, highest reliability, availability, and maintainability as per CENELEC standards
  • Supports below configurations
    • 2DP - Straight line
    • 3DP - Point Zone/Set of Point
    • 3DP-2S - Two consecutive sections (IBS) on a straight line
    • AS - Auto signaling
  • Fool proof method for avoiding wrong configuration at site
  • FSK 1200bps fault tolerant data transmission on single pair 0.5 quad cable / OFC voice channel
  • Track occupancy information available at each detection point
  • Train detection up to 250Km/h
  • Trolley protection circuit not required
  • Works with 90-R, 52kg, 60kg and worn-out rails
  • Local or remote data logging for 15000 events
  • Provision of VR and PR relays
  • Wide input voltage operation from 16.8 VDC to 32.0 VDC


2DP Configuration

  • Operation on straight lines - station or block section
  • Communication using one pair quad cable
  • Preparatory Reset configurable either with or without piloting
  • PR and VR contacts at detection points

3DP Configuration

  • Operation on point Zones / Set points
  • Communication using one pair quad cable
  • Detection and clearing at any points
  • Preparatory Reset with LV
  • VR contacts at all detection points

3DP-2S (IBS) Configuration

  • Operation on two consecutive sections on a straight line (IBS configuration)
  • Communication using one pair quad cable for each section
  • Preparatory Reset configurable either with or without piloting
  • PR and VR contacts at detection points