KL3314 by Beckhoff

The KL3314 is an analog thermocouple input module manufactured by Beckhoff for the KL Analog Input Modules series. Mounted beside other Bus Terminals, it converts four independent temperature or millivolt signals into numerical data usable by a PLC. By placing acquisition electronics close to sensor wiring, the module reduces electromagnetic pickup and simplifies cabinet layout, making it suitable for ovens, dryers, HVAC plants, and other industrial processes that rely on distributed temperature feedback.

Each channel updates every 250 ms, a period suited to typical thermal processes. Conversion resolution is 0.1 °C per digit, and the value is sent as a signed 16-bit number in 0.1 °C two's-complement format. The four channels together occupy 8 bytes of cyclic data, with identical space reserved for diagnostics. Field and logic domains are separated by 500 V of galvanic isolation, minimizing ground loops. Total error remains under ±0.5% FS because of internal cold-junction compensation. Open-circuit monitoring flags broken leads, and a millivolt mode is available for sensor checks.

The terminals accept thermocouple leads through a 2-wire connection that keeps wiring straightforward inside the cabinet. Eight push-in terminal points carry signal, reference, and shield conductors while leaving space for supply looping. The housing snaps onto a 35 mm DIN rail and automatically engages the Bus Terminal connector. Its internal K-bus protocol allows upstream couplers to read status without extra mapping. Electrically independent input circuits allow mixed sensor types to share one module, and the enclosure meets the IP20 protection class required for installation inside closed control panels. The front contacts allow individual channels to be tested without disturbing adjacent terminals.