Interbus was developed specially for use in machine systems and is specified in DIN E19258/EN50170. The Interbus system is based on a ring structure with active coupling between the devices. The bus access process is a straightforward master/slave system. The data from the master loops through the slaves as in a large shift register. The so-called remote bus can support a maximum of 512 devices with a distance between the slaves of up to 400 m. The entire length of the circuit, if constructed in copper cable, can therefore be up to 13 km. Each slave works on the basis of its active coupling like a repeater, refreshing the signal. The remote bus uses a 6-core cable and RS485 physics. The data transmission is 500 kbaud. The Interbus parameterization is very simple since the Interbus can read in its own connected stations via an identification cycle. The master thereby recognizes how many and which devices are connected.
All Interbus device manufacturers are obliged to have developed devices certified by the Interbus Club e.V. That means that the devices can be incorporated into any Interbus systems.
Configuration is started with the Interbus via an identification cycle. The master thereby automatically recognizes all connected devices. Identification takes place via an identification code, which is stored in each device, and a long code, which contains the length of the transferred data.
The extensive diagnostic functions of the Beckhoff Interbus devices allow rapid fault localization. The status of the network connection, the device status, the status of the inputs and outputs and of the power supply are displayed by LEDs.
Compact Box modules for Interbus are available for all relevant industrial signals. In addition to digital and analog input and output modules including thermocouple and RTD inputs, there are also incremental encoder interfaces available for displacement and angle measurement in addition to serial interfaces to solve a large number of communication tasks.
The Interbus Coupler Box gathers the I/O data from the Extension Box modules over the interference-free IP-Link fibre optic cable. It detects the connected modules and automatically allocates the input and output data to the process image. Both data consistency and a clear separation of input and output data are ensured. The Coupler Box has four digital inputs and four digital outputs. Other kinds of signal are available in the Extension Box.