
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 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 Controllers 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.
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.
- The MR340 series should be used in all new applications in lieu of the MR302/MR303/MR304/MR310/MR320 series Incremental Encoders.
Legacy Product Information, MR30X / MR31X / MR32X Series
- 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.
- The MR30X series can be ordered under their new MR34X part numbers as explained in Application Note AN127. Original documentation for MR30X series can be found here: MR302-1 Controller, MR302-1 Manual, MR302-2 Controller, MR302-2 Manual, MR303 Linear Encoder, MR304 Mini Rotary Encoder
- The MR320 series is still available by special order. Original MR320 documentation can be found here: MR320 Controller, MR320 Manual, MR322 Encoder, MR324 Hollow Shaft Encoder, MR325 Encoder, MR326 Encoder, MR328 MRI-Safe Encoder
- The MR310 series is still available by special order. Original MR310 documentation can be found here: MR310 Controller, MR310 Manual, MR312, MR314 Hollow Shaft Encoder, MR316 Encoder, MR318 MRI-Safe Encoder
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:


MR342 Rotary Sensor
MR342 series Incremental Encoder offers 100-360ppr resolution in an industry standard size 58mm encoder housing. The sensor is ideal for motor speed control and low resolution position monitoring. Like all of Micronor’s Fiber Optic Encoders, the MR342 is a passive sensor which is immune to EMI and is ATEX classified as a “simple apparatus” for use in all manner of hazardous locations and explosive environments.

MR348 MRI Safe Rotary Sensor
- MRI facilities
- EMC test labs
- Anechoic chambers
- Industrial applications operating under extreme electromagnetic fields

MR346 Size 90mm Rotary Sensor
- IP66 ingress rating (resistant to powerful water jets)
- Resolution options: 256 and 360 ppr
- Optical link can extend up to 2000 meters
- Standard (-40°C/+80°C) or Extended (-60°C/+125°C) Temperature option

ZAPPY340 Configuration Software

MR343 MRI Safe Linear Sensor
MR343 Linear Incremental Encoder is an innovative, all optical, non-metallic solution for MRI applications due to both its immunity and invisibility to magnetic fields. The sensor provides 0.1mm positional resolution. With a MR340 Controller, the encoder’s optical link can extend up to 1600 meters.

MR344 High Resolution Hollow Shaft Sensor
MR344 High Resolution (1024ppr) Hollow Shaft Incremental Encoder is ideal for closed-loop feedback of variable frequency drives (VFD) and other high capacity/high voltage motor drives operating in challenging environments. The MR344 is a totally passive sensor, immune to EMI and can transmit interference-free over distances up to 2500 meters. An Extended Temperature Option offers -60°C to +125°C operation.

MR340-1 DIN Controller
The MR340-1 DIN Rail Mount Controller works with any of the MR340 series Fiber Optic Incremental Encoders – rotary or linear. The sensor is connected to the controller via an industry-standard 62.5/125μm duplex multimode fiber optic link. The controller keeps track of position and also calculates the RPM or linear speed of the connected encoder. Both position and speed can be read via built-in SSI, Modbus/RS485, USB or Analog Interface. The analog output can be configured for either ± 10V or 4-20mA output.