The present application relates to the electronic field of railways, and in particular to the traction control system for electric multiple units. A host processor of the traction control system for electric multiple units is connected to a subordinate computer board via a CPCI bus. The traction control system for electric multiple units comprises a fast computing board, a network module and a debugging module. An instruction is passed to the subordinate computer board via the CPCI bus, and meanwhile, the subordinate computer board passes status information to the host processor via the CPCI bus to realize overall control on the interior of the traction control system for electric multiple units. Bidirectional communication between the signal sampling board and the fast computing board is realized by a high-speed differential LinkPort bus to realize quick control on the inverter power module and the four-quadrant power module. Bidirectional communication between the network card and boards of the I/O module is realized by a CAN bus, and digital signals and analog signals sent by boards of the I/O module are transferred to the host processor via the CPCI bus to ensure stability and reliability in information transmission of the traction control system for electric multiple units.

A universal input/output circuit for building automation is provided that may avoid issues related to capacitor soakage, thereby giving more accurate measurements of electric resistance. To mitigate capacitor soakage, the voltage between the input/output terminals is held constant. A programmable source drives a current through a resistor that connects to the input/output terminals. The circuit then measures a value of electrical resistance. The measurement yields a voltage signal which is transferred from the input of an analog-to-digital converter to the input of a digital-to-analog converter. A unity gain amplifier applies the output voltage of the digital-to-analog converter D/A to one of terminals. The circuit is configured such that the voltage signal at the output of the amplifier matches or substantially matches the voltage obtained from the resistance measurement.