Bullet Sensors & Transducers e-Digest, Vol. 67, Issue 5, May 2006: Product News

    (ISSN 1726- 5479)


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High Resolution Hollow Shaft Fiber Optic 

Rotary Encoder


Micronor’s new MR314 ZapFREEä High Resolution Fiber Optic Rotary Encoder was designed for large drive and rotary shaft applications requiring EMI immunity, higher resolution (1024ppr) and the mounting convenience of a traditional hollow shaft encoder package. There are no integral electronics within the encoder housing and the all-optical design requires just a single optical fiber connection – the utmost in simplicity, reliability and ease of installation.


The MR314’s totally passive design outperforms conventional optical and magnetic rotary encoders over a wide range of harsh and/or hazardous environments: wide extended operating range (-60°C/+150°C); outdistances copper cable; intrinsically safe and ATEX-compliant; immune to EMI/RFI and ground loops; unaffected by high magnetic fields; and radiation resistant. Special versions can be easily engineered for thermal-vac environments.


The “passive” MR314 optically links to the “active” MR310 ZapFREEä Remote Encoder Interface (REI) Module via a single 62.5/125 multimode fiber link – up to 1000 meters (3280 feet) away. With its convenient DIN-rail mount, the MR310 module is co-located with the PLC or other system interface electronics where power supply connections and conventional electrical interface connections are easily made. The module offers a wide range of standard interfaces: direct quadrature outputs (both open collector and line driver), separate multiplier/divider quadrature outputs, two fully-programmable analog outputs (4-20mA and +/-10V), and PC-friendly RS232/RS422/RS485 serial interface.


In addition to the MR312/MR314 native incremental encoder mode of operation, the MR310’s firmware also allows the encoder to emulate a multiturn absolute encoder. The internal 24-bit counter can track up to 32,768 revolutions of the 1024ppr MR314 or 23,201 revolutions of the 360ppr MR312. Either a software command or TTL signal input to the MR310 establishes a Calibration or Zero reference (reseting the counter to zero). An external battery back-up is required to maintain operation during power interruptions. A combination power supply/back-up battery trickle charger is available. Capacity of the battery determines the amount of back-up time. 


Like the original MR312 Shafted Fiber Optic Encoder, all MR3XX series encoders utilize telecom-proven WDM (wavelength division multiplexing) technology by assigning each internal optical path (A or B) to a wavelength so that all wavelengths/paths can be combined onto a single fiber (patent pending). It was deliberate to avoid the use of multiple fibers as this tends to drive up the cost of the optical harness. A single-fiber cable is inherently more cost effective and more reliable than any multi-wire or multi-fiber or hybrid cable assembly - and easier to handle and install as well. It just doesn’t get any simpler.


Fiber Optic Rotary Encoder




Dennis Horwitz

Vice President, Sales & Marketing, Micronor Inc.

Tel: (805) 499-0114, fax: (805) 499-6585

E-mail: dennis.horwitz@micronor.com



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