MR342 Encoder

MR342 Encoder

ZapFREE® Size 58mm Fiber Optic Incremental Encoder

The MR342 series ZapFree® Fiber Optic Incremental Sensor is an entirely passive, intrinsically safe, fiber optic incremental rotary encoder – ideal for a wide range of harsh and hazardous environmental applications. The passive, all-optical sensor connects to the remote Controller via a standard duplex 62.5/125 multimode optical fiber link.

The remote MR340 Controller Modules transmit and convert optical signals to/from the sensor. The Controller’s multiple built-in interfaces insure compatibility with industry standard motor drives, PLCs, quadrature counters and motion control systems.


Measurement Parameters
Resolution 100, 128, 256, 360ppr (Consult Micronor for special requirements)
Max Speed 8,000 RPM continuous
Mechanical Parameters
Moment of Inertia 1.0585E-6 kg*mm2
Starting Torque 1.28E-5 N*m
Max Shaft Loads Radial = 80 N (18 lbf), Axial = 40 N (9 lbf)
System MTBF

L10 Bearing life calculated at 50% of max. radial and axial load at 2500 RPM:

1.78E+05 hours (20.3 years)

Optical Interface
Optical Interface LC Duplex, 62.5/125μm Graded Index Fiber, 0.275NA, Type OM1
Link Length Up to 2000 meters with MR340 Controller
Explosive Atmospheres Inherently Safe, Simple Mechanical Device
EX Classification Inherently safe, simple mechanical device when used with MR340 Controller
IEC Ex EPL Mb/Gb/Gc/Db/Dc
Environmental Attributes
Temperature/Humidity -40°C to +80°C, 0%-95% RH (non-condensing)
Ingress Protection IP64 (splash proof)
Physical Attributes
Housing Dimension Ø 58mm x 58mm
Unit Weight 210 g (7.25 oz)
Materials Body: Anodized Aluminum; Shaft and Bearings: Stainless Steel

Specifications subject to change without notice


  • 100% passive sensing design – no electronics whatsoever
  • 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
  • Temperature range -40°C to +80 °C
  • Special versions can be engineered for radiation and vacuum environments
  • DIN rail mount and OEM PCB controller available

Ordering Information

MR341-X03YYY Where X=Resolution and YYY=Optical Interface
X Options: C=256ppr, D=360ppr, E=512ppr
YYY Options: C1R5=1.5m Pigtail, C03=3m Pigtail
MR340-1 DIN Rail Mount Controller


Quick Ship Configurations

MR340-0 OEM PCB controller
MR340-1 DIN Rail Mount Controller
MR342-D06C1R5 Size 58mm Encoder, 360ppr, Duplex LC Pigtail Length=1.5m
MR342-D06D00 Size 58mm Encoder, 360ppr, IP-LC Interface