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ATEX Approved Absolute Encoders

The ATEX Directive embodies the European requirements for equipment used in potentially explosive atmospheres. ATEX certification requires the manufacturer to demonstrate that the equipment can be safely operated in a potentially explosive athmosphere. It became mandatory on June 30th 2003.

ATEX draws attention to the non-electrical hazards and requires a consideration of these with respect to explosion safety.

Absolute rotary encoders are capable of providing unique position values from the moment they are switched on as well as immediately after a power loss. This is accomplished by scanning the position of a coded material. All positions in these systems correspond to a fixed code. Even movements that occur while the system is without power are translated into accurate position values at once when the encoder is powered up again

Measuring Principles - Optical encoders are made up of a revolving shaft with a code disc and an optoelectronic scanning unit consisting of a screen and photoreceptors. Infrared light from an LED source passes through the code disc and the screen behind it. At every angle position a different sequence of photoreceptors are blocked from light by dark segments on the code disc.

Functionality - The OPTOCODE (OCD) series uses a highly integrated Opto-ASIC providing a resolution up to 16 bits (65536 steps) per turn, as well as additional incremental signals. Without backup batteries the measuring range is increased up to 16384 revolutions using mechanical gearing.

Interfaces - All OPTOCODE (OCD)models are available with hollow or solid shaft versions and are IP 65 protected to withstand harsh industrial environments. Special stainless steel or explosion-proof encoders for hazardous areas are also available. All models transmit digital measurement values to control systems either by parallel, serial or any common field bus interface. Standardised interfaces feature simplified connections and stable data transmission while also safeguarding investment assets:

Within the Absolute rotary encoders range we have the following products:

• Profibus-DP
• CANopen
• Devicenet