Elements of functional diagram allowing to get information about controller's state.
All of the available from the functional diagram, controller resources: system registers, IO subsystem, and additional drivers included in the system software - are appeared on a protected address space of the controller's internal memory.
By "Input register" unit the user is able to extract and use the controller status data and information received by the controller from the outside world. For example, information about an electric potential on any terminal of the controller or contents of a data packet received over the CAN bus.
Refer to the documentation for the specific controller model.
Element "Input register" can be connected to a network, directly to function block input or write register thereby setting them to the value, synchronously with a value change in the corresponding register of the controller.