RIO for Process Automation (RIOforPA) is a Common Application Profile for PROFINET and PROFIBUS defined in [RIO PA].
RIOforPA defines the following application classes (see [RIO PA], sec. 5.1):
Figure 2 – Application Classes for RIOforPA
“… The application class RIOforPA Digital Input defines functions for mapping of digital input signals from the process to input data transferred to the IO controller. The application class RIOforPA Analog Input defines functions for mapping of analog input signals from the process to input data transferred to the IO controller.
The application class RIOforPA Digital Output defines functions for mapping of output data transferred from the IO controller to digital output signals to the process. The application class RIOforPA Analog Output defines functions for mapping of output data transferred from the IO controller to analog output signals to the process.
Additional functions like fieldbus integration or HART mappings etc. are not in the scope of the profile.
Instances of the application classes will be realised as channels. A channel may have a connection to a sensor or actuator (physical channel) or not (logical channel). …” (see also [RIO PA] sec. 5.1).