Encoders

Encoders and position sensors convert mechanical movement into an electrical signal that a drive, PLC or controller can use. This is a small category at Seven Star LLC in Oman with three listed products: an Autonics incremental rotary encoder, a Balluff Micropulse magnetostrictive linear position sensor and an HB Products linear short-stroke position transmitter in an Ex version. The range is growing, and other encoder models can be sourced on request.

Rotary encoders and linear position sensors

An incremental rotary encoder outputs a fixed number of pulses per shaft revolution, usually on two channels shifted by 90 degrees so the controller can read direction, plus a reference pulse once per turn. It is the usual choice for speed feedback and length measurement. An absolute encoder reports a unique position value and keeps it through a power loss. Magnetostrictive linear sensors measure the position of a magnet along a rod or profile without contact, which is why they are common inside hydraulic cylinders and on presses, gates and valve actuators. Short-stroke position transmitters give a continuous signal over a short travel, typically for valve stem or actuator position.

Data needed to quote an encoder

For a rotary encoder send the shaft type and diameter, flange, resolution in pulses per revolution, output circuit (line driver, push-pull or open collector), supply voltage and connection type. For a linear sensor send the stroke length, output signal, mounting style and, for use in the GCC oil and gas sector, the required Ex marking.