Because of high transmission speed and synchronicity, the EtherCAT protocol enables high performance and, at the same time, cost-effective control, even with a simple CPU in the EtherCAT master. The controller can have efficient access to 200 different I/O terminals via the BK1120 EtherCAT Bus Coupler.
Industrial Ethernet is well-established in the electronic terminal block market. Beckhoff offers the user two I/O systems with the Bus Terminal and the EtherCAT Terminal system. The EtherCAT Terminals are designed for high performance und the flexible topology that only EtherCAT offers. In contrast to original Bus Terminals, where the fieldbus signal is implemented within the Bus Coupler on the internal, fieldbus-independent Terminal Bus, the EtherCAT protocol remains fully intact down to each individual terminal.
Continuity with the Beckhoff Bus Terminal system is guaranteed by the BK1120 EtherCAT Bus Coupler. Thus, the fast real-time Ethernet system can also use the Bus terminals with more than 200 different signal types, including safety functions. The Beckhoff Bus Terminal has become standard technology in automation in the last few years with millions of examples in use worldwide.
New areas of application for distributed I/Os
EtherCAT is also suitable for low and medium control ranges. The combination of EtherCAT fieldbus and Bus Terminal system provides high-performance and cost-effective control technology. The EtherCAT master requires no special plug-in card and can be easily implemented on any existing Ethernet controller. Control and closed loop control concepts can be easily realised, even with simple CPUs, due to the extremely high performance of EtherCAT.
Among other things, EtherCAT improves system performance without changing the CPU by shifting the mapping task from the control CPU into the EtherCAT system. Pre-sorted data are transferred to the control computer’s RAM via Direct Memory Access (DMA). With traditional fieldbuses, a physical process image is generated and mapping occurs in the controller’s CPU. This process can occupy up to 30 % of the CPU’s capacity. The physical process image created is not usually compatible with the variables in the controller.
The physical process images are mapped to the logical images during mapping. Valuable CPU time is used to look for individual bits in the data and to copy them into variables. The work must be carried out again in reverse order before issuing the data. With EtherCAT, mapping is shifted to the fieldbus slaves. This takes load off the master. The CPU can carry out the complete data exchange with only a few accesses required to the Ethernet controller, since it is only necessary to send one EtherCAT Frame for small to medium sized system parameters.
The BK1120 is also particularly suitable for highly distributed applications such as for conveying technology, since Ethernet cable lengths of up to 100 m between individual nodes are possible.