A rotary encoder reports position or speed back to a drive or controller. Replacing one means matching both the signal it produces and the way it mounts. Get the signal wrong and the controller won't read it.
Incremental or absolute?
- Incremental: outputs pulses as it turns — specified by PPR (pulses per revolution). Loses position on power-off (re-homes on startup).
- Absolute: reports an exact position even after a power cycle — single-turn or multi-turn, specified in bits of resolution.
Match the output / protocol (must match the receiver)
- Incremental: quadrature A/B/Z channels, signal type (TTL/RS-422 line driver, HTL/push-pull, open collector), and supply voltage (5V or 10–30V).
- Absolute: the protocol — SSI, BiSS, EnDat, or a fieldbus (PROFINET, EtherCAT, CANopen).
Mechanical fit
- Shaft style: solid shaft (with a coupling), or hollow/through-bore / blind-hollow that slips onto a shaft.
- Shaft or bore diameter, body size, and flange (clamping, synchro/servo, square).
- Connection: cable or M12/M23 connector, and the pinout.
Send us the encoder
Tell us the part number (or PPR/resolution, output type and shaft/flange), and we'll cross-reference an encoder from brands like Heidenhain, SICK, Pepperl+Fuchs, Baumer or Dynapar and quote it.