Low-potential twenty-channel scanning switch

The utility model relates to a low-potential twenty-channel scanning switch, belonging to the technical field of thermal resistance measurements. The scanning switch comprises a rear panel, low-potential wiring terminals, multigang low-potential switches, flexible connectors, a bracing frame, stepping motors, a front panel control display board, a C8051F one-chip microcomputer control circuit board, and communication serial ports, wherein the front panel control display board comprises a nixie tube channel display board and a keyboard, and the low-potential wiring terminals are fixed on the rear panel. A control system giving priority to a one-chip microcomputer realizes the automatic control of a five-gang switch to achieve the transition of twenty channels and realizes the control of a three-gang switch to achieve the free changeover between forward and backward directions of the motors.