An infusion set includes a base and an inserter removably connected to the base. If a power source monitor circuit itself is normal, the power source monitor circuit reads a detection signal from a detection circuit, and checks power sources. An electronic automatic control device maintains a constant distance and a constant pressing force between the fixed roll and the transfer roll by feedback of detection signals sent from the respective sensors, wherein the servomotor is driven by the electronic automatic control device to adjust the position of the transfer roll. Finally, a present main identifier and a present sub-identifier are calculated according to the four indices corresponding to the four maximal values, wherein the cross-correlation calculation is conducted on the TII signal and the PRS of every two adjacent sub-carriers.