Limit switch with transmitter supply for monitoring current or voltage signals

General Information
Input / Output
Electrical Data
Mechanical Data
Certification / Approvals
Additional Information


  • LC display for limit values and bar graph
  • Input: 1 x Analog (U, I)
  • Output: 1 x transmitter power supply
  • 2 relays for limit monitoring (with change-over contacts)
  • Transmitter supply 196to250 V AC, 97to127 V AC, 20to250 V AC/DC

Fields of application

  • Plant and apparatus engineering
  • Switch cabinets
  • Process monitoring
  • Process control


The RTA421 limit switch from Endress+Hauser is used for monitoring and safeguarding industrial processes. The device evaluates current signals (0/4...20 mA) and voltage signals (0/2 to 10 V) and switches two independently operating relays at the output if previously defined limit values are exceeded or not reached. Both limit values can be read simultaneously in the display. Applications, e.g. pump controls in wastewater technology, level monitoring in tanks can thus be implemented at low cost.

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Valentine Godin

Great product and customer care! Reliable, fast and honest... I have recently purchased 2 pieces of equipments; their service has been spot on from start to finish, understanding my needs, providing useful advice and rapid assistance when it was required! Highly satisfied, I highly recommend their teams and would definitely work with them again in the future!

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