CANopen, a kind of communication protocols, is based on the intelligent field bus(CAN bus). It was developed as a standardized embedded network with highly flexible configuration capabilities. It provides standardized communication objects for real-time data(Process Data Objects, PDO), configuration data(Service Data Objects, SDO), network management data(NMT message, and Error Control), and special functions(Time Stamp, Sync message, and Emergency message). Nowadays, CANopen is used in many various application fields, such as medical equipment, off-road vehicles, maritime electronics, public transportation, building automation and etc. I-87123 main control unit is specially designed for the master device of CANopen protocol. It supplies many features for users, such as dynamic PDO, EMCY object, error output value, SYNC object, _and etc.