Beckhoff KL1804 Programmable Logic Controller Module

Beckhoff KL1804 is a four-channel digital input terminal for the K-Bus that accepts 24 V DC field signals and transmits them galvanically isolated to the master automation device. Belonging to Beckhoff's KL1xxx bus-terminal family, the module presents four input bits in the controller's process image and requires no address or configuration settings. Its inputs are rated for 24 V DC with a 3 ms input filter, offering typical input current of 3 mA per channel; the K-Bus current draw is typically 10 mA, and the module's power-contact current is about 1 mA plus load; the device provides up to 500 V isolation between field and K-Bus. Physical and connection specs include dimensions of 12 mm width by 100 mm height by 68 mm depth, weight around 60 g, and conductor options: solid wires 0.08–1.5 mm2; stranded wires 0.25–1.5 mm2; ferrules 0.14–0.75 mm2; solid wires connect directly by plug-in, while stranded wires and ferrules use a spring-clamp actuated by a screwdriver. Technically, KL1804 uses 3-leitertechnik (three-wire technique) and presents a 4-bit process image width, making it suitable for deploying digital sensors such as pushbuttons and basic sensors in industrial automation where galvanic isolation and compact form factor matter.