Single CS31 Bus on CPU COM Port

The following picture describes basic operation of HA-CS31 system - a typical scan cycle of an AC500 CPU with redundant CS31 slave (CI590-CS31-HA).

System Structure AC500 CPU

Status of the inputs connected to CI590-CS31-HA is transferred to both CPUs simultaneously in every CS31 cycle. The CPUs process HA-CS31 function blocks along with the application program. At the end of the program, the generated outputs are transferred to respective buffers in the CI590-CS31-HA via CS31 Bus. Depending on the control byte and on diagnosis events, the CI590-CS31-HA selects one of the output buffers. Then, the buffer content is transferred to physical outputs through the I/O Bus.

Data transfer between the CPUs is watched by HA_CS31_CONTROL function block. HA_CS31_DATA_SYNC function block collects data from the primary CPU and creates a data table which is transferred to the secondary CPU via ETHERNET link. Depending on data size, data transfer may take more than one cycle.