The Lightbus system is a fast and secure serial fieldbus system. Immunity to electromagnetic influences, total electrical isolation of the connected modules from one another and high transmission speed even over large distances are the critical advantages of fibre optic technology. Combined with an optimised and compact telegram structure, the Lightbus achieves a very high transmission rate of 2.5 Mbaud. The Lightbus has a ring structure; up to 254 stations can be operated in one ring. Economical and easily handled standard fibre optic technology is used for the data transfer.
The modules are automatically addressed by the master in the order they are connected. During start-up, the system will check the cable attenuation and compare the number of projected and actually connected slaves. Special I/O parameters can be set by means of the KS2000 software (serial connection to the configuration interface of the Fieldbus Box).
The extensive diagnostic functions of the Beckhoff Lightbus devices allow rapid fault localization. The error telegrams are output in special counters, so that, in case of an interruption of the fibre optic ring, the location can be determined and displayed. Additionally, each slave has various diagnostic options for reporting the current status to the master. 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.
Cables and connectors
The Beckhoff range of ready-assembled cables makes installation a great deal easier. Wiring errors are avoided, and commissioning is more rapidly completed. The range includes fieldbus cables, power supply cables, sensor cables and accessories. The plastic fibre optics are easy to make up. The Lightbus cable is identical to the fibre optic used for the IP-Link connection.
Compact Box modules for Lightbus 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 Lightbus 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 signals are available in the Extension Box.