The CiA 437 application profile defines the CANopen interfaces for photovoltaic (PV) control systems. This includes interfaces to PV controllers, PV inverters, wind direction sensors, temperature sensors, radiation sensors, energy sensors, power sensors, solar panel tracking systems, etc. The three-part specification comprises general definitions, pre-defined communication objects, and process data specification. When implementing the profile, device manufacturers may supply diverse applications using the same electronic CANopen interface implementation and simply adapting the required functionality. A system designer may combine CANopen devices from different manufacturers implementing the required profile-compliant functionality. The according spare parts are then also available from different sources. For development, analysis, and maintenance of the devices, off-the-shelf CANopen tools may be used.

The profile defines several virtual devices (non-divisible functions) supporting a set of mandatory and optional application objects. A physical CANopen device implements one or more virtual devices. But a virtual device may not be distributed to several physical devices. A virtual device supports one or more functional elements (device numbers, e.g. inverter 1, inverter 2, inverter 3) distinguished by the index and sub-index number of the implemented objects. A mechanism for automatic device number assignment is proposed (not mandatory) in CiA 437-1. The PV controller is a virtual device with NMT manager functionality and the capability of automatic device number assignment. It also provides the SDO client functionality to the SDO servers of other devices. A PV system may consist of much more networked devices than 127 (node-ID limit in one CANopen network), requiring interconnection via several CANopen networks. To transfer data between the networks is possible using remote emergency and remote SDO functional elements (see CiA 302-7). Hereby, the PV controller acts as the system manager. It also optionally provides an interface to other distributed electrical power generation systems (e.g. wind-craft, diesel, biogas, etc.) and optionally links the PV system to the electrical power distribution control system. Part 1 also defines which application objects have to be implemented by a certain virtual device including the access direction (e.g. ro, rw, wo) and the category (mandatory, conditional, or optional).