KL4022 by Beckhoff

The KL4022 is an analog current output terminal manufactured by Beckhoff for the KL Analog Output Modules series. This two-channel current source converts digital setpoints into proportional process signals for actuators and control loops. It mounts directly on a 35 mm DIN rail, forming a continuous row with adjacent Bus Terminals. In industrial automation systems, the terminal allows a PLC to drive valves, speed references, or transducers without separate signal conditioners. The terminal draws its logic supply from the I/O backplane, which keeps wiring requirements minimal.

Each channel delivers a programmable 0 to 20 mA output and operates as a single-ended circuit referenced to the bus ground. A 12-bit digital-to-analog converter provides 4,096 discrete levels across the output range. The process image provides 2 × 16 bits during each cycle, combining command and diagnostic information in one word per channel. Proper regulation is maintained when the loop resistance remains below 500 ?; a higher resistance can cause current foldback. All conversion electronics receive power from the system's 24 VDC power rail, so the terminal does not require an auxiliary supply.

The housing is only 15 mm wide, projects 70 mm deep, and stands 100 mm high, allowing installation in densely arranged control cabinets. The front spring-clamp terminals provide two outputs and maintain the required single-ended topology. The IP20 enclosure protects against accidental finger contact with live internal parts during normal operation. The permitted ambient temperature ranges from 0 °C to 55 °C during operation. Storage temperatures can range from -25 °C to 85 °C, allowing the module to remain installed during extended facility shutdowns. Its narrow housing leaves more rail space available for neighboring terminals while retaining accessible front wiring.