Glossary · Industrial communication

PROFINET conformance class

Also known as: Conformance class (PROFINET), CC-A, CC-B, CC-C, CC-D

German: PROFINET-Konformitätsklasse

In PROFINET, a conformance class is one of the defined feature sets CC-A, CC-B, CC-C and CC-D that state which functions a device or network supports: CC-A basic real-time (RT) communication, CC-B additional network diagnostics and topology information, CC-C isochronous real-time (IRT) with bandwidth reservation, and CC-D PROFINET over Time-Sensitive Networking (TSN).

Industrial communication
Standards

In one sentence

PROFINET conformance classes CC-A to CC-D group device features: RT, network diagnostics, IRT for motion control, and PROFINET over TSN.

Example

A packaging line's conveyors and remote I/O run as CC-B devices over RT, while the synchronized servo axes of the case packer need CC-C devices and IRT-capable switches.

How it applies

Engineering: The conformance class is chosen from the application: most factory I/O runs over RT (CC-A or CC-B); isochronous motion control needs CC-C with PROFINET IRT, where every device and switch in the IRT path must support it. CC-D moves PROFINET onto Time-Sensitive Networking (TSN); check product availability before planning it.
Network design: The class of a network is limited by its weakest component. A standard switch in an IRT path breaks the time reservation, and CC-B diagnostics need switches that provide topology and SNMP data.
Certification: Conformance classes are part of PI device certification. A certified class describes what a device supports, not that a particular plant network is designed correctly.
Documentation: The documentation team states the conformance class of each device and of the network, the switches that may be used, and the cycle times the application relies on.

RT vs. IRT

RT frames are prioritized but share the network with other traffic, which is enough for cycle times in the millisecond range. IRT reserves a time slot in each cycle and synchronizes the devices, which gives the low jitter that motion control needs.