This device profile series specifies the application interface for absolute rotary and linear encoders. The most recent edition comprises four parts:

• CiA 406-B: Functional behavior and parameters
• CiA 406-C: Mapping to CANopen CC
• CiA 406-F: Mapping to CANopen FD
• CiA 406-J: Mapping to J1939

Part B based on the legacy CiA 406 document specifies the process data, the configuration parameters, and the diagnostic information. The encoder manufacturers supply various markets with encoders implementing the same electronic interface according to CiA 406 series. Besides position and velocity values, the profile specifies also process data for acceleration and jerk values. Furthermore, the document describes several configuration parameters, e.g. the code sequence (complement) that determines the counting direction in which the output code is to be increased or decreased. The resolution parameter is used to configure a given number of steps for each revolution. In addition, the profile covers complete cam functionality taking hysteresis into account.

The encoder profile specifies two distinct operation modes:

• Periodical mode: The current position value is sampled and transmitted periodically by means of the PDO event timer; the period is configurable.
• Synchronous mode: The current position is sampled and transmitted after the reception of the SYNC message sent by the host controller or any other synchronization entity.

Only one mode can be used at the same time.

Three classes of CANopen encoders are defined:

• Class 1 devices support normal resolution encoding and diagnostic functions without alarm and warning capabilities. Optionally heartbeat and Layer Setting Services (LSS) are implemented.
• Class 2 devices support all Class 1 functions. Additionally, scaling and preset functions are implemented as well as alarm and warning functions.
• Class 3 devices support Class 2 functions and high-resolution position values. Optionally, they feature CANopen Safety. Heartbeat and LSS as specified in CiA 305 are mandatory.

Any class can support CANopen Safety.

The CiA 417 profile series references partly the CiA 406 process data and configuration parameters for car position units. However, the object dictionary indexes are different.

Besides the mapping to CANopen CC PDOs, Part C specifies also the mapping of position values into SRDOs (Safety-Related Data Objects) according to EN 50325-5 (CANopen Safety). The CANopen Safety encoder application configuration is validated using the same CRC polynomial (CRC-CCITT) as for the communication configuration (see EN 50325-5).

Part F specifies the mapping of encoder process data to CANopen FD PDOs. Three TPDOs are pre-defined. The mapping depends whether it is a single- or a multi-channel device. As in CANopen CC PDOs, only position values are pre-mapped. Additional process data can be mapped by means of configuration. The maximum length of these PDOs is 64 byte.

Part J enables manufacturers to implement the CANopen dictionary in a J1939-connectable encoder. The primary purpose of J1939-connectable encoders is the usage in body applications in trucks and mobile machines. The process data such as position value and velocity value are mapped into parameter groups (PGs) with registered PGNs (PG numbers). The process data such as position, velocity, and acceleration is mapped into parameter groups. The EPOS parameter group is used for normal resolution encoders and the EHRPOS parameter group can be used for 64-bit encoders. The speed and acceleration are carried in other PGs. Another PG maps both position and speed.

For configuration and diagnostic purposes CANopen SDO and Emergency protocols are mapped into standardized PGs (see CiA 510).

Additionally, CiA provides the legacy CiA 406 version 4.1.0 specifying the functional behavior including process data and configuration parameters as well as the CANopen CC mapping. This predecessor approach is currently in many encoders implemented. It complies widely with CiA 406-B and CiA 406-C.