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MR340 Rotary and Linear Incremental Encoder Series


MR340 Series

Fiber Optic Incremental Encoders

Fiber Optic Incremental Encoders are typically used to sense the motion and speed of a motor shaft or linear actuator where conventional electronic-based encoders and resolvers are inadequate. Typically the user’s control system is looking for A/B quadrature signals for which electro-magnetic interference and noise causes system errors.

Micronor MR340  series Fiber Optic Incremental Encoders are based on an all-optical passive sensor design which optically connects to a remote controller via a standard duplex OM1 62.5/125 multimode fiber optic link spanning distances up to 2000 meters. The Controller offer much more interface capability besides A/B quadrature outputs. The additional built-in analog (4-20mA, ±10V) and digital interfaces (RS485, USB, Modbus RTU) can also be user-programmed to output speed or position status.


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Product line:

  • MR340 series is Micronor’s 3rd Generation Fiber Optical Incremental Encoders – comprising both rotary and linear models. The new series provides a lower cost, intermountable replacement for the MR320 series while adding a small form factor rotary and linear option. Resolution is available up to 1024ppr or 100μm.
  • Special non-metallic, all-dielectric rotary and linear encoders for medical MRI and high voltage environments – MR343 Linear and MR348 Rotary.



  • 100% passive sensing design – no electronics whatsoever
  • Linear and rotary sensor configurations
  • 256ppr to 1024ppr resolution, depending on sensor model
  • Sensor can be installed in all manner of hazardous locations and potentially explosive atmospheres – mines, gas and dust
  • Immune to EMI and RFI for safe use in and around medical equipment and “noisy” industrial environments
  • Immune to lightning and high voltages
  • Outdistances copper, link lengths to 2000 meters
  • Standard temperature range -40°C to +80°C
  • Extended temperature range on some models -60°C to +125°C
  • DIN rail mount controller

Micronor Fiber Optic Incremental Encoders provide interference free feedback in challenging environments and applications as diverse as medical devices to welding robots, and steel mills to mines. The diagram below illustrates a typical application where the fiber optic encoder is used to provide noise-free, closed loop feedback for precise control of a VFD or High Voltage Drive System:


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Legacy Product Information for MR30X / MR31X / MR32X Series

  • The MR340 series replaces all previous and obsolete Micronor FO Incremental Encoder series – MR310 and MR320. The MR340 series sensors are intermountable but not interchangeable as they require a MR340-1 Controller for internal optical compatibility.
  • The MR340 series supersedes and interchangeable with the previous MR30X series as the MR340 series is based on the Generation 2.5 MR30X optical platform.  The change is in part number only – MR340-1 replaces MR302-1, MR341 replaces MR304, and MR343 replaces MR303.
  • For complete cross reference information by model and MR34X replacement, consult Application Note AN127, New MR340 Series FO Incremental Encoders Replace MR30X / MR31X / MR32X Series.
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