MR346 Encoder

MR346 Encoder

ZapFREE® Size 90mm Fiber Optic Incremental Encode

The MR346 ZapFREE® Heavy Duty 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 Module transmits and converts 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


100, 128, 256 and 360ppr (Consult Micronor for special requirements)

Max Speed

8,000 RPM continuous

Note: De-rate maximum speed by 100 RPM per °Celsius when operating about 60°C for maintaining shaft seal integrity..

Mechanical Parameters


Body: Anodized Aluminum; Shaft and Bearings: Stainless Steel

Moment of Inertia

2.5095E-6 kg*mm2

Starting Torque

3.0E-2 N*m

Max Shaft Loads

Radial = 140 N (31 lbf), Axial = 70 N (15 lbf)

System MTBF

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

8.96E+05 hours (102.3 years)

Optical Interface


Duplex LC on pigtail or ODVA IP-LC receptacle

Fiber Type

Duplex MM 62.5/125µm, Graded Index, 0.275NA

Link Length

Max distance is the lesser of 2000m (8300 ft) OR 2-way optical loss of 12dB at 850nm

Physical Attributes

Housing Dimension

Ø90 mm x 82.5 mm

Unit Weight

615 g (21.5 oz)

Explosive Atmospheres

Inherently Safe, Simple Mechanical Device

Ex classification

Inherently safe, simple mechanical device when used with MR340 Controller


EPL Mb/Gb/Gc/Db/Dc


EPL Mb/Gb/Gc/Db/Dc

Environmental Attributes


Standard: -40°C to +80°C / 0% to 95% RH (non-condensing)

Extended Option: -60°C to +125°C / 0% to 95% RH (non-condensing)

Ingress Protection

IP66 (strong water jets and temporary immersion)

Specifications subject to change without notice


  • 100% passive, all-optical sensing design
  • Sensor can be installed in all manner of hazardouslocations 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 that “zaps” conventional electronics-based encoders
  • Outdistances copper, link lengths to 2000m
  • Standard model operates -40°C to +80°C
  • Extended Temperature option covers -60°C to +125°C
  • Special versions can be engineered for radiation and thermal-vac environments

Ordering Information

MR346-X12YYYZ Where X=Resolution, YYY=Optical Interface, and Z=Temperature Range
X Options: C=256ppr, D=360ppr
YYY Options: C1R5=1.5m Duplex LC Pigtail , C03=3m Duplex LC Pigtail, D00=IP-LC Interface
Z Options: (Blank)=Standard -40°C to +80°C, E=Extended -60°C to +125°C (not applicable to D00 interface option)
MR340-1 DIN Rail Mount Controller


Quick Ship Configurations

MR340-0 OEM PCB Controller
MR340-1 DIN Rail Mount Controller
MR346-D12C03 Size 90mm Encoder, IP66, 360ppr, Duplex LC Pigtail=3m
MR346-D12D00 Size 90mm Encoder, IP66, 360ppr, IP-LC Interface