HASSDAC-720P is a SSDAC providing high availability of the  axle counting system by means of redundancy. It is capable of using either one or two web detectors. It is a fully redundant two out of two fail safe system with intelligence for error recovery. It enables railways to achieve higher line capacity by eliminating the requirement of one paper line clear train movement in case of failure of one axle counter.

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HASSDAC provides the following benefits over SSDAC:

  1. Redundancy provided in wheel counting circuit, processing circuit, communication circuit/link, relay driver circuit, and DC-DC converter. Fully redundant.
  2. Any Failure in one unit does not affect train running.
  3. Failed unit provided with reset command automatically after 12s to recover from error/failure. The failed/erronous system goes in preparatory-reset mode. 
  4. After movemnt of one train, the unit in preparatory reset atains clear state automatically and redundancy is restored.
  5. Separate counters are provided in vital relay unit for each unit that gets incremented only when an auto reset is applied. This way, an eye can be kept on the number of auto reset applied to both the units.
  6. Reset box has an indication to show that one of the unit is not working.
  7. Station master needs to provide reset only if both the processing units fail simultaneously.
  8. Station master's reset counter measures only the manual reset applied by SM.

HASSDAC-720P has been designed in accordance with RDSO specification No. RDSO/SPN/177/2012 following CENELEC standards.