Lisandro Piacentini

Encoder interface cables carry differential position signals that are highly susceptible to noise, crosstalk, and impedance discontinuities. Correct cable selection — including characteristic impedance, conductor gauge, shielding type, and jacket material — determines whether the encoder achieves its specified noise immunity and signal quality at the required cable length.

Cable shield termination and ground loop prevention are the most common sources of encoder signal noise in servo motor installations. This article defines the correct shielding method for motor and encoder cables, identifies the conditions that create ground loops, and describes practical mitigation techniques.

Glass scales outperform metal tape scales in optical encoders across three critical parameters: coefficient of thermal expansion, grating uniformity, and sustainable accuracy at elevated temperatures. This article establishes when glass is technically required and when tape scales are an acceptable alternative.

Inductive rotary encoders operate without a line-of-sight requirement between sensor and scale, making them immune to particulate and liquid contamination that disables optical systems. This article covers the operating physics, ingress protection ratings, and verified industrial applications where inductive encoders are the technically correct choice.

The three principal optical encoder architectures — transmissive, reflective, and interferential — differ in accuracy, physical layout, and suitability for precision motion applications. Selection depends on resolution requirements, installation envelope, and contamination tolerance.

Magnetic rotary encoders use Hall-effect sensors and permanent magnets to detect angular position. Their low cost and compactness make them the dominant technology in cost-sensitive applications. However, susceptibility to external magnetic fields, reduced accuracy-to-size ratio, and temperature sensitivity limit their use in high-precision or EMI-heavy environments.