The nonprofit CiA (CAN in Automation) has released the CANopen specification for sleep and wake-up handling of CANopen devices.
The CANopen specification specifies services and protocols to switch-off and to switch-on CANopen devices from the network. The specification complies also with CAN transceiver chips providing low-power mode and selective wake-up functionality as standardized in the ISO 11898 series.
The services enable the power management master (PM master), which is residing at the active CANopen NMT master, to control the local Sleep finite state automaton (FSA) and the remote Sleep FSA of all power management devices (PM devices) in the network. The PM master uses CAN data frames with the CAN‑ID 691h to send commands to PM devices. PM devices use CAN data frames with the CAN‑ID 690h as well as the EMCY write protocol as specified in CiA 301 to transmit requests to the PM master. The additional error codes are also defined in the specification. Furthermore, the services allow an automatic transition to Sleep state of a PM device, in case there are no live-signs of the PM master.
Battery-powered CANopen devices, for example in Pedelecs (CiA 454) or in special-purpose cars (CiA 447), need such sleep and wake-up functionality, in order to reduce power consumption during longer standstills. The same applies for battery-powered service robots and automated-guided vehicles with embedded CANopen networks.
“Up to now, all those sleep and wake-up-capable CANopen devices used proprietary protocols,” explained Holger Zeltwanger, CiA Managing Director. “The release of CiA 320 unburdens system designers to invent on the application level sleep and wake-up functionality.” Now, they can buy interoperable products providing sleep and wake-up capability.
News and reports