The Bus Terminal Controller BC4000 is a Bus Coupler with integrated PLC functionality and has a fieldbus interface for the Interbus. The BC4000 is an intelligent slave and can be used as a decentralised intelligence in the Interbus system. Interbus has been established as an open fieldbus system since 1987. It has a ring structure, and up to 256 stations can be operated in a ring. Data transmission takes place at 500 kbaud. Therefore sensor and actuator data can be transferred over great distances.

One unit consists of the Bus Terminal Controller, any number of terminals between 1 and 64, and a bus end terminal. The Bus Terminal Controller is programmed using the TwinCAT programming system according to IEC 61131-3. The configuration and programming interface on the BC4000 is used to load the PLC program.

The controller recognises the connected terminals and automatically generates the affiliations of the inputs/outputs to the bytes of the process image. The first input/output signal is inserted in the first bit of one word (LSB), beginning from the left. The controller inserts further signals in this word. Inputs and outputs are clearly separated. The controller automatically begins a further word if the number of inputs or outputs exceeds 16 bits.

Controller for distributed signal processing

The programming system TwinCAT for the BC4000 operates, independently of the manufacturer, in accordance with IEC 61131-3. The PLC programs can be written in five different programming languages (IL, FBD, LD, SFC, ST). In addition, TwinCAT offers extensive debug functionalities (breakpoint, single step, monitoring, …), which facilitate commissioning. It is also possible to perform adjustment and measurement of the cycle time.