CANopen profile for weighing devices

The nonprofit CiA (CAN in Automation) association has released version 2.0.0 of the CiA 461 profile specification series. This series comprises four parts specifying the CANopen interfaces of weighing devices. A simple CANopen weighing network consists of load cells, compensation sensors, scales and HMIs (human machine interface) or indicators. Such a network can comprise several devices of the same kind. Load cells and scales feature optionally locally or remotely connected compensation sensors. Scales provide optionally locally or remotely connected indicators. These devices are controlled and operated by a weighing process control entity located typically in the scale. This device supports also CANopen manager capabilities (NMT producer, configuration manager, and error control services such as Heartbeat) to configure, control, and monitor the other CANopen devices. If a scale does not provide a weighing controller, the corresponding functionality can be implemented in a PLC (programmable logic controller) or an industrial PC.

Version 2.0.0 of CiA 461 series introduces functional safety features as standardized in EN 50325-5 (CANopen Safety). The profile documents specify SRDOs (safety-related data objects). They are mapped to two Classical CAN data frames containing bit-wise inverted information using different CAN-IDs. The trade-for-sale function is the same as in the previous version. Also, the authentication and encrypting functions have not been changed.

Weighing systems compliant with this CANopen profile are intended for industrial applications including truck scales and weighbridges. On-board weighing equipment with CANopen connectivity is specified in the CiA 459 series.