BK3150-0900 by Beckhoff

The BK3150-0900 is a bus coupler produced by Beckhoff for distributed I/O systems. Acting as a field-level gateway, it links a group of Beckhoff I/O terminals to a PROFIBUS DP master so that analog and digital process variables can be exchanged with the controller in real time. Its modular terminal interface supports sensor acquisition, actuator control, and machine status reporting through a single network connection. The coupler mounts at the beginning of the terminal assembly and manages communication between the connected modules and the higher-level control system.

This unit handles 128 analog inputs and outputs and an additional 256 digital inputs and outputs, allowing mixed-signal stations to operate through one network node. The PROFIBUS interface supports transfer rates of up to 12 Mbaud, helping maintain responsive data exchange when the network includes several high-density couplers. Control electronics operate from a 24 VDC supply; startup current reaches 2.5 times the continuous demand, while normal operation draws up to 320 mA. A D-Sub 9-pin connector provides the PROFIBUS connection, and power contacts within the terminal assembly can carry field power to connected devices. Internal isolation barriers have a dielectric strength of 500 V, separating the communication circuits from the supply domain.

The compact housing provides IP20 protection when installed in a suitable control cabinet. The built-in terminal bus distributes data and power to as many as 64 standard terminals, while an extension can increase the supported terminal count to 255. The cyclic PROFIBUS process image accommodates 128 bytes, helping conserve controller memory in distributed automation systems. Connected terminals share a combined current limit of 10 A through the spring-contact backplane. Housing dimensions of 44 × 100 × 68 mm allow installation on a DIN rail without exceeding the depth of typical control enclosures. The terminal stack extends to the right of the coupler, allowing the station to be arranged according to the required combination of analog, digital, and specialty I/O modules.