3.2 OPC UA for PROFINET Remote IO terms

3.2.1 Controller

A Controller is a host running a program which reads and writes the Process Values used to control an automated process. The control is usually done in cycles consisting of reading the Input Process Value, processing the Input, calculating the Output, and finally writing the Output Process Value.

3.2.2 Device

A Device is a stand-alone unit exchanging cyclic data with a Controller. Devices are usually configured by the Controller and may also generate acyclic data like alarms or diagnostic information. A Device may consist of several modules and Submodules.

3.2.3 A RIO Output Channel comprises all Function Blocks, Functions and Variables used for processing of an analog or digital electric output signal. Typically, a RIO Output Channel is used to transfer an Output Process Value to an electric signal. In addition, RIO Output Channels may process a Readback Value.

3.2.4 A RIO Channel Group is an aggregation of RIO Channels.

3.2.5 Substitute ValueThe Substitute Value can be used in place of the Process Value if it cannot be trusted and safely used.

3.2.6 Process Value QualifierThe Process Value Qualifier provides additional information for one Process Value indicating if it can be trusted and safely used.