In this paper

we report our work on the software and hardware architecture of the DCCT system for SSRF where top-up mode is being used.Matlab is used to simulate two methods of beam current calculation.The system resolution of the DC current measurement with 2 Hz system bandwidth could be better than 0.38 μA when arithmetic mean of whole cycle algorithm is applied.The beam lifetime calculation algorithm is optimized to use two points in the curve fitting procedure based on the characters of the top-up mode.The algorithm of finding the confidence level is also discussed and is verified to be accurate in data prediction as well as fast in convergence by using the practical data fetched in the laboratory.The flow chart of the software layer is given to show how the code is implemented.