KL3302 by Beckhoff

The KL3302 is an analog input terminal manufactured by Beckhoff as part of the KL Analog Input Modules series. This compact terminal accepts two independent sensor channels and converts their signals for the fieldbus-capable Bus Terminal system, allowing controllers to record temperature gradients or microvolt levels directly from the machine frame. Its role in industrial automation is to bring precise low-level measurement to distributed I/O nodes, eliminating the need for standalone transmitters while keeping the cabinet footprint minimal.

Each channel uses 2-wire connection technology, so the field device and the module share a common return conductor, reducing the terminal count inside the enclosure. Sampling is performed at a default conversion interval of 250 ms; this timing balances noise suppression with update speed for slow-changing thermal processes. The first-order digital filter has its first notch at a default frequency of 25 Hz, attenuating power-line ripple that can interfere with low-amplitude signals. The internal controller packages every reading into 2 × 16 bits of input data, providing enough room for signed values and diagnostic flags. Overall measurement accuracy remains within ±0.5% FS, keeping deviation small across the rated operating range.

The module attaches to a 35 mm DIN rail and draws logic power directly through the K-bus, so no additional supply wiring is necessary. It is engineered for control cabinets rated to IP20, meaning the housing prevents access by fingers and protects against solid objects larger than the applicable limit, but it is intended for protected indoor environments. Temperature channels resolve changes in sensor output at 0.1 °C/digit, while millivolt inputs provide a voltage resolution of 4 µV/digit; these increments let the PLC detect fine process changes without oversampling. Two physical inputs are available, and an optional status word containing 2 × 8 bits can be transmitted for alarm flags. Because open-circuit detection is not provided, external wiring checks are recommended when wire-break detection is critical.