Device for inputting elevator call commands and elevator control system

An elevator control system comprising:

• a plurality of elevator calling devices, each elevator calling device comprising:
• one or more button units, each of the button units comprising:
• a switching element;
• a variable resistance circuit coupled with the switching element, the variable resistance circuit comprising a button switch and a display element coupled in parallel, and a resistance value of the variable resistance circuit varying with a state of the button switch;
• and
• a control unit configured to determine a state of a corresponding button switch based on the resistance value of the variable resistance circuit within each of the button units, to apply a pulse width modulation signal having different duty cycles onto a control terminal of a corresponding switching element based on the state as determined, and to generate an elevator calling request;
• and
• an elevator controller coupled with the elevator calling devices and configured to generate a control command in response to the elevator calling request.