Vending machine door monitoring system
View Patent ↗A vending machine door monitoring system for an audit system is provided. This door monitoring system may utilize the same door switch utilized by the vending machine controller (VMC) in order to detect the state of an access door for the vending machine. This door monitoring system may have a separate power supply for applying a back-up voltage to a door circuit in the event that the VMC fails to supply the voltage. The door monitoring system may be further configured to detect a state of the door circuit regardless of the order in which the terminals from the door switch are coupled to the audit system.
1. An audit system for a vending machine system comprising a housing including a door having a closed state and an open state, a door switch, and a vending machine controller (VMC) coupled to the door switch via a door circuit, said VMC applying a voltage across the door switch, said audit system comprising:
an auxiliary circuit coupled to the door circuit; and
an audit control system configured to detect the status of the door switch by monitoring the voltage from the VMC, wherein the audit control system is configured such that if the audit control system detects cessation of the voltage from the VMC, the audit control system applies an auxiliary voltage across the door switch to detect the status of the door switch.
2. The system of claim 1 , further comprising:
a battery for supplying the auxiliary voltage across the door switch.
3. The system of claim 1 , wherein:
said audit control system is configured to perform an initialization process in which the audit control system determines a state of the door circuit corresponding to the open state of the door.
4. The system of claim 3 , wherein:
said audit control system performs the initialization process at startup.
5. The system of claim 1 , wherein:
the VMC comprises a voltage terminal and a ground terminal; and
the audit system comprises a first input terminal and a second input terminal coupled to the voltage terminal and the ground terminal, said audit control system being configured to monitor the voltage passing through the door switch regardless of whether the first input terminal is coupled to the voltage terminal or the ground terminal.
6. The system of claim 5 , wherein:
the audit system comprises a sensor circuit coupled to the voltage terminal and the ground terminal, said sensor circuit configured to pull a positive voltage to a monitoring logic to monitor the voltage passing through the door switch.
7. The system of claim 1 , wherein:
said audit system further comprises a communications interface and is configured to transmit an open door status message to a host system via the communications interface upon detection of the open state of the door.
8. The system of claim 7 , wherein:
said audit system is further configured to transmit a door status update message to the host system via the communications interface after a predetermined period of time following the transmission of the open door status message.
9. The system of claim 8 , wherein:
said door status update message comprises an indication of a current state of the door and the length of time the door has been in the current state.
10. A method of monitoring operation of a vending machine system, said method comprising:
monitoring a door circuit between a first power source and a door switch, said door switch engaging an access door for the vending machine system;
in response to a cessation of a voltage from the first power source, applying a voltage from a second power source and continuing to monitor the door circuit between the first power source and the door switch to detect at least a current status of the door switch.
11. The method of claim 10 , further comprising:
performing an initialization process in which a state of the door circuit corresponding to the open state of the door is determined.
12. The method of claim 11 , wherein:
said initialization process is performed at startup of an audit system.
13. The method of claim 10 , wherein:
said monitoring the door circuit comprises connecting an audit system to the door circuit, said audit system automatically detecting a voltage line from the first power source.
14. The method of claim 13 , wherein:
the audit system comprises a sensor circuit coupled to a voltage terminal and a ground terminal, said sensor circuit configured to pull a positive voltage to a monitoring logic to monitor the voltage passing through the door switch.
15. The method of claim 10 , further comprising:
upon detection of an open state of the access door, transmitting an open door status message to a host system via a communications interface.
16. The method of claim 15 , further comprising:
transmitting a door status update message to the host system via the communications interface after a predetermined period of time following the transmission of the open door status message.
17. The method of claim 16 , wherein:
said door status update message comprises an indication of a current state of the door and the length of time the door has been in the current state.
18. A method of operating a vending machine system, comprising:
monitoring a door circuit coupling a door switch and a vending machine controller (VMC) using an audit system;
detecting a cessation of voltage in the door circuit; and
responsive to the cessation of voltage applying an auxiliary voltage to the door circuit to continue to monitor the door circuit and detect at least a current status of the door switch.
19. The method of claim 18 , wherein:
performing an initialization process in which a state of the door circuit corresponding to the open state of the door is determined.
20. The method of claim 19 , wherein:
said initialization process is performed at startup of an audit system.
21. The method of claim 18 , wherein:
said monitoring the door circuit comprises connecting an audit system to the door circuit, said audit system automatically detecting a voltage line from the first power source.
22. The method of claim 21 , wherein:
the audit system comprises a sensor circuit coupled to a voltage terminal and a ground terminal, said sensor circuit configured to pull a positive voltage to a monitoring logic to monitor the voltage passing through the door switch.
23. The method of claim 18 , further comprising:
upon detection of an open state of the access door, transmitting an open door status message to a host system via a communications interface.
24. The method of claim 23 , further comprising:
transmitting a door status update message to the host system via the communications interface after a predetermined period of time following the transmission of the open door status message.
25. The method of claim 24 , wherein:
said door status update message comprises an indication of a current state of the door and the length of time the door has been in the current state.
26. A vending machine system, comprising:
a housing including a door having a closed state and an open state;
a door switch;
a first means for applying a voltage across the door switch and for detecting a state of the door switch; and
a second means for detecting the state of the door switch, wherein said second means applies an auxiliary voltage across the door switch in response to detection of a cessation of the voltage applied by the first means.
27. The system of claim 26 , further comprising:
a battery for supplying the auxiliary voltage across the door switch.
28. The system of claim 26 , wherein:
said second means is configured to perform an initialization process in which the second means determines a state of the door switch corresponding to the open state of the door.
29. The system of claim 28 , wherein: said second means performs the initialization process at startup.
30. The system of claim 26 , wherein:
said first means comprises a voltage terminal and a ground terminal; and
said second means comprises a first input terminal and a second input terminal coupled to the voltage terminal and the ground terminal, said second means being configured to monitor the voltage passing through the door switch regardless of whether the first input terminal is coupled to the voltage terminal or the ground terminal.
31. The system of claim 30 , wherein:
said second means comprises a sensor circuit coupled to the voltage terminal and the ground terminal, said sensor circuit configured to pull a positive voltage to a monitoring logic to monitor the voltage passing through the door switch.
32. The system of claim 26 , further comprising:
a means for generating an open door status message to be transmitted to a host system via a communications interface upon detection of the open state of the door.
33. The system of claim 32 , wherein:
said means for generating the open door status message is further configured to transmit a door status update message to the host system via the communications interface after a predetermined period of time following the transmission of the open door status message.
34. The system of claim 33 , wherein:
said door status update message comprises an indication of a current state of the door and the length of time the door has been in the current state.