The Vital latching interface system RS4.B.24.0.24 is a latching relay used in Railway wayside applications where an operator command will allow changing wiring configuration following 2 distinct and exclusive positions. The system latching feature allows keeping the status imposed by the latest command. One of the system key features is his modular design providing the operator opportunities to program large number of contacts (Left/Day or Right /Night).


The system architecture includes:

  • One or many sub-systems, wired to wayside equipment depending on the user preference mapping.
  • One or two 19’’ Rack, handle the different sub-systems
  • Control unit localized on the left of the rack ensure that every contact have been made in both Day and Night mode.


  • DAY/NIGHT switch (change over latch) function used for interlocking modification.
  • Route latch function
  • Switch machine safety latch

block diagram


The system is designed to comply with safety level SIL4 according to CENELEC EN 50129 for the following properties:

  • If no contact is made (Left / Day OR Right / Night), no opposite contact can be made.
  • If one contact is made (Left / Day OR Right / Night), only switch active command can involve opposite contact to be made.

The Vital latching interface system RS4.B.24.0.24 incorporates latching relays compliant to the EN61810-3 standard. The contacts of these relays are weld no transfer contacts. The galvanic isolation between coil/contacts and contacts/contacts is 1,500 ACV.


24 NC and 24 NO contacts

6U card packaging

Low power consumption

Up to 10 modules per system

Up to 200 useful contacts

Example of use in a weighing system (Y-shaped):

  • Card in 6 U format
  • SIL4 switching system
  • Compatible with a 19” rack
  • Low power consumption
  • Up to 10 cards per system
  • Up to 200 contacts
  • Can be controlled by a PLC
  • Suitable for Y-positioning functions
  • 24VDC power supply – EN50155 compliant







Switching system with local control key


Download datasheet

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