Modicon M580, Hardware Reference Manual

In a modular PAC system, the controller controls and processes the application. The local backplane identifies the controller. In addition to the controller, the local backplane contains a power supply module and may contain communication processing modules and input/output (I/O) modules. The controller is in charge of: • configuring the modules and devices present in the controller configuration • processing the application • reading the inputs at the beginning of tasks and applying the outputs at the end of tasks • managing explicit and implicit communications Modules may reside in the local backplane with the controller or they may be installed in remote drops at a distance from the local backplane. The controller has built-in capabilities to act as the RIO controller that manages communications between the controller and the X80 EIO adapter modules that are installed in each remote drop.