Abstract: An elevator door monitor eliminates the need to use customized input devices or modules in an elevator door monitoring system. The elevator door monitor employs differential amplifier circuits, one circuit for each of a plurality of signals to be monitored regarding an elevator car, each signal corresponding to a separate input into a microcontroller unit (“MCU”). Each differential amplifier circuit electrically communicates with a respective input terminal of the MCU, which can include a memory resource storing settings associated with respective elevator control parameters. A user can enter each setting using a peripheral input device. These settings provide system customization in lieu of hardware components, allowing the elevator door monitor to function as a universal system that can monitor a variety of elevators.