In this paper, the generator excitation regulator as the control object, studies the data tracking between the dual microcomputer excitation control system and bumpless transfer, in order to ensure the system real-time data tracking, the accuracy of fault detection and quick failover, especially the design of the control system of a redundant hot standby based on double DSP, through the eCAN communication network data through the eCAN network to follow, mailbox function complete dual data tracking, the proper use of the DSP interrupt service subroutine for fault identification, finally using DSP rich software functions of fault alarm and switching. The experimental test of generator excitation regulator of above ideas developed data follow and fault based switching system, operation results show that: the typical faults in the excitation conditions, system data real-time, accurate tracking, disturbance of high fault free switching, system reliability and maintainability improve.