The AX5000 series was developed specifically for use with the EtherCAT real-time Ethernet system. The outstanding features of EtherCAT are particularly beneficial for Drive Technology. They include short cycle time, synchronicity and simultaneity. EtherCAT enables very short cycle times, even in networks containing a large number of devices. A cycle time of 125 µs enables set values and actual values to be exchanged cyclically with more than 100 drives. Naturally, the AX5000 can also deliver high performance with “normal” cycle times – EtherCAT imposes practically no limits in this respect.
The distributed clocks implemented in the EtherCAT Slave Controller ensure high synchronicity (low jitter) and ideal simultaneity (no temporal offset). Both values are significantly less than 1 µs. Synchronicity is important for the individual axes so that their own subordinate control loops can synchronise with the cyclic signal with the required precision. Simultaneity also enables distributed axes to be operated with the same time base for a common task.
High-speed control algorithms
Familiar drive profile
The SERCOS interface is acknowledged and appreciated worldwide as a high-performance real-time communication interface, particularly for Motion Control applications. The SERCOS profile for Servo Drives is standardised in IEC 61491. It is also used for EtherCAT and is implemented in the AX5000. This means that for users with SERCOS experience, the drive will seem familiar, since the process data layout and the IDN parameter and status machine were retained. The AX5000 thus combines the benefits of the familiar drive interface with the wide range of EtherCAT features.
Communication via EtherCAT according to IEC/PAS 62407
Line, tree or star: EtherCAT supports almost any topology. The bus or line structures used for fieldbuses are also available now for Ethernet. Unlike with cascaded switches or hubs, there are no restrictions in terms of the number of nodes. With 100 m cable length between two devices and up to 65,535 nodes per segment, the potential network size is almost unlimited. Particularly useful for system wiring is the combination of line and branches or stubs. Since EtherCAT also supports hot connection of line segments, system sections can be switched off flexibly.
Low connection costs
Networking costs are made up of connection costs for master and slaves, infrastructure costs, and costs for wiring and commissioning of the network. EtherCAT offers convincing advantages in all respects: As the only true real-time Ethernet network, EtherCAT requires no special plug-in cards with communication processors in the master, i.e. the existing IPC Ethernet interface is sufficient. Cost-effective slave controller chips, which are available on-board in the AX5000 without additional cost, are used in the slave. EtherCAT requires no expensive connectors or active infrastructure components such as switches. As a result, no additional wiring or parameterisation is required. With EtherCAT, network commissioning is extremely straightforward: Addresses are allocated automatically and do not have to be set manually. Due to the high performance offered by EtherCAT, no network tuning is required – unlike many other systems.
Experience with fieldbus systems shows that availability and commissioning times crucially depend on diagnostic capability. Only faults that are detected quickly and accurately as well as located precisely can be corrected quickly. Therefore, special attention was paid to exemplary diagnostic features during the development of EtherCAT. Apart from breaking point detection and localisation, the protocol, transfer physics and topology of the EtherCAT system enable individual quality monitoring of each individual transmission segment. Gradual or changing sources of error such as EMC influences, defective push-in connectors or cable damage are detected and located, even if they do not yet overstrain the self-healing capacity of the network.