In automation, rotary encoders are used as sensors for angle, position, speed and acceleration. Linear motion can also be measured through the use of spindles, gear racks, measuring wheels or cable pulls.
Rotary encoders convert a mechanical input into electrical signals, which can be processed by counters, tachometers, programmable logic controllers and industrial PCs.
Moreover, reference runs when the machine is switched on or after power failures are no longer required as the current position value is available immediately. Parallel absolute encoders transmit the position value to the analyzing electronics through several parallel cables. Serial absolute encoders transmit their output data via standardized interfaces and protocols.
In the past, point-to-point connections were frequently set up for serial data transmission but today fieldbus systems are being used more often.
The Pepperl+Fuchs rotary encoder portfolio includes the most varied range of current interfaces for absolute encoders to be found on the market:
- Parallel Interface
Incremental rotary encoders supply a certain number of pulses for each shaft revolution. Speed is measured by counting the pulses for a period of time. To calculate angle or the distance covered, pulses are counted starting from a reference point.
Dual channel quadrature output encoders feature two signal outputs that are 900 out of phase with each other. This permits the controller to determine direction of rotation and perform bi-directional positioning tasks.
In addition, three-channel incremental encoders have a third signal channel (known as “zero”, or reference, signal) that provides a single pulse for each revolution.
Rotary encoders for harzardous areas flame proof or intrinsically safe
Pepperl+Fuchs offers rotary encoders with two different ignition protection types. They are distinguished between the ignition protection type “flame proof enclosure” (EEx d) and the ignition protection type “Intrinsic Safety” (EEx i).
Ignition protection type EEx d
- Incremental encoders
- Absolute encoders
Ignition protection type EEx i
In case of the ignition protection type EEx i the voltage and current levels are kept at such a low level that the occurrence of an ignition spark is prevented, thus preventing the ignition of an explosive atmosphere. The following devices are designed in accordance with this ignition protection type:
- Incremental encoders
- Internally, cable is wrapped around a spring-loaded drum that turns the encoder’s shaft when the cable is extended
- Standard 58 mm diameter encoders mount to the adapter with synchro mounting elements
- Cable pulls are an excellent tool for linear measurements with high resolution