CiA^® 401: CANopen device profile for generic I/O modules

The CiA 401 device profile specifies the CANopen interface for modules with generic analog and digital inputs and outputs. The default first TPDO and first RPDO support up to 64 digital inputs, respectively up to 64 digital outputs both grouped byte-wise. The remaining default PDOs transmit or receive up to 12 analog inputs respectively up to 12 analog outputs both with a 16-bit resolution. All TPDOs are triggered by change-of-state. Therefore, default TPDOs containing analog inputs are disabled.

Besides the default byte-wise access to digital I/Os, optional bit-, word-, and double-word access may be supported. Besides the default 16-bit resolution for the analog I/Os, optional 8-bit, 32-bit, floating-point and manufacturer-specific resolutions may be supported.
Several parameters are specified to configure the input and output behavior (e.g. trigger conditions for inputs, output behavior in case of internal device failures). For analog I/Os, signal conditioning and filter functions are not standardized. For these cases, it is advisable to use the CiA 404 profile for analog sensor applications.

In the annex of the CiA 401 specification there are implementation hints for specific I/O modules such as joysticks. Joysticks are regarded as input modules with analog inputs for the three dimensions (x, y, z). A further TPDO contains by default one byte of digital information. In this byte, the three bits are used to enable the memory function for the three dimensions (x, y, z).