Two same type AC500 PLCs are required as central hardware components. Each PLC is equipped with at least two Ethernet ports at a processor module or at a communication module. The two PLCs, called PLC A and PLC B, are linked by Ethernet to exchange and synchronize information (Sync). Connections to the AC500 peripheral field devices (I/O) are performed via Ethernet as well.

⮫ Further information on which CPU type and library to be used.

The following table gives an overview of the different High Availability variants possible with AC500.

The figures are indicative, depend on chosen architectures, system size, network and CPU/communication modules used.

¹⁾ Number of CI52x recommendation based on performance or max. number of sockets.

⮫ More details on supported Modbus clients.

²⁾ Limited by CPU performance, number of CM574 modules number of CS31 clients and process data limits.

³⁾ Depends on system size and CPU type.

⁴⁾ For details on certain S500-eCo modules not supported, see the Automation Builder release notes, Appendix 1.

⁵⁾ 2ETH onboard ports - port extensions via CM5640-2ETH: 2 separate ETH ports/communication module for separate networks (no additional sockets or coprocessing, not switched, all ports in different subnets).

⁶⁾ Based on HA bits switchover, depending on failure case.

⮫ “Use case descriptions” ⮫ “Task configuration recommendations for HA system”

⁷⁾ Field network: If CI52x are used with their 2 ports as part of a ring: In the moment of a network switchover single telegrams may be destroyed: - for V2 ETH onboard: Standard TCP delays repeats by 500 ms - for V3 CPUs onboard/CM5640 or V2 CPU using CM597: A special HA-FW ensures fast repeats of typ. ~50ms (settable).

⁸⁾ If CAN is used for Lifecom2, maximum CAN cable length between CPUs must be less than 40 meters (Baud rate: 1 Mbit/s).