A new data acquisition and analysis system for unexpected, rapid changes in plasma parameters has been developed. The scheme is designed for the high-temperature plasmas of long-time tokamak operation. The post trigger samples of conventional computer-automated measurement and control modules are utilized during a sudden event. The scheme of the method is described. This method is applied to the long discharges of the TRIAM-1M tokamak. The system works well for an unexpected and rapid termination of a discharge and could provide desired data. It is demonstrated that a new system with proper monitoring can track the unexpected, rapid changes in plasma parameters.