K9202B | HIMA Cabinet Roof Fan

In contrast to mono operation, the entire design of a redundant system is intended to ensure availability. Redundant input modules safely record the values measured by redundant sensors.They exchange data with the processor modules via the safety-related I/O processing modules.The measured values are cyclically queried and compared by the redundant processor modules, and then processed by the user program. The user program’s results are sent to the I/O processing module, which writes them to the redundant output modules. The output modules thus control the field level, e.g., the actuators. The example in Figure 9 shows a redundant structure of field level and extension rack. During redundant operation, the signal is processed via both system buses A and B. The system buses A and B between the I/O processing modules are implemented in a patch cable.