A power supply monitoring and control circuit using a microcontroller to remotely monitor and control the functions and conditions of a power supply. The power supply monitoring and control circuit is coupled to the primary and secondary sides of a power supply to monitor important voltage and current signals of the power supply, such as the output voltages and currents, and to control the various parameters of the power supply such as the output voltage and current limits. Analog to digital interface circuitry is provided to convert the power supply voltage and current signals to digital signals which are retrieved by a microcontroller which converts the digital signals to numbers representing the values of the power supply signals, and then stores the numbers. The microcontroller is also interfaced to reference and feedback signals of the power supply to control the power supply's operation. The microcontroller further keeps track of the total elapsed time of operation and the total number of times the power supply has been powered up. The power supply monitoring and control circuit operates as a slave to a host computer system so that a system operator can retrieve all of the monitored information and can control the operation of power supply. The host computer system communicates with the power supply monitoring and control circuit through a serial link, so that the host computer can be remotely located. The present invention also provides self-calibration to assure accurate data.