KL3142 by Beckhoff

The KL3142 is a modular analog input terminal produced by Beckhoff within the KL Analog Input Modules series. Designed for decentralized control architectures, the unit digitizes low-level process currents and forwards the results through the Bus Terminal system so that a PLC can respond to real-time sensor feedback. The terminal adds multipoint current measurement without requiring separate signal conditioners in the cabinet, which streamlines wiring and maintains a compact footprint in industrial automation cells.

During normal operation, the terminal provides 4 single-ended current channels, each wired through the front contacts using a 2-wire connection that minimizes field cabling. Internally, a successive-approximation converter samples each channel with a 12-bit resolution, allowing the controller to detect small changes in process signals. The digitized values are transferred onto the backplane as a 4 × 16-bit process image, so the host CPU receives one 16-bit word per channel without additional packing. Electrical power for the signal conversion circuitry is routed automatically through the system's K-Bus, eliminating external supply terminals and keeping the I/O slice thin. This bus connection also carries process data between the terminal and the associated bus coupler.

The housing measures only 15 mm in width, 70 mm in depth, and 100 mm in height. Its compact size allows multiple terminals to mount side by side on a standard 35 mm DIN rail while maintaining the required ventilation clearances, and the installation position can be varied without affecting performance. A molded latch secures the terminal to the rail, while open-circuit detection on every channel reports wiring breaks to the PLC software. The front contacts provide direct access to the field wiring, helping keep the terminal arrangement organized inside a control cabinet. With an enclosure rating of IP20, the module protects against contact with fingers and similarly sized solid objects but does not provide protection against water.