Cash flow monitoring system

• US 4,357,605 A
• Filed: 04/08/1980
• Issued: 11/02/1982
• Est. Priority Date: 04/08/1980
• Status: Expired due to Term

• Current Assignee: Cybex International
• Original Assignee: Metallurgical Research, Inc.
• Inventors: Clements, Kenneth P.
• Primary Examiner(s): Pitts, Harold I.
• Application Number:
  US06/138,795
• Time in Patent Office: 938 Days
• Field of Search: 340/147 P, 340/152 T, 340/310 R, 340/310 A, 340/170, 340/825.06, 340/825.14, 340/825.02, 340/825.54, 340/825.55
• US Class Current: 340/538
• CPC Class Codes: H04B 2203/5408 using protocols
• CPC Class Codes: H04B 2203/5416 by adding signals to the wave form of the power source
• CPC Class Codes: H04B 2203/5445 Local network
• CPC Class Codes: H04B 2203/5458 Monitor sensor; Alarm systems
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 2203/5491 using filtering and bypassing
• CPC Class Codes: H04B 2203/5495 having measurements and testing channel
• CPC Class Codes: H04B 3/542 the information being in digital form

Abstract

A computerized monitoring system which incorporates the power lines that provide electrical power to the remote devices as the physical communications medium of a serial data bus for the computer system. The system comprises a central computer and a plurality of computerized sensor modules within the individual remote devices. The central computer and each of the sensor modules has associated with it a respective data link for coupling respective signal generating and receiving means to the power distribution lines and for manipulating the signals to and from a form suitable for transmission on the power distribution lines. Phase shift keying is used wherein binary bits of data are represented as 180° phase shifts of the pulses in a carrier pulse train. A data transmission rate of approximately 15,000 baud with a carrier frequency of 120 kHz is typical. A polling signal includes a preamble of pure carrier frequency, followed by the serial number of the device being polled, followed by the data (or instructions) defining the message content. Each data link has its own clock for generating a pulse train at a frequency very close to the common carrier frequency, and includes means for bringing its own carrier frequency pulse train approximately into a predetermined phase relationship with the carrier train that is appearing on the power lines.

Claims

1. A system for monitoring the operation of a plurality of remote electrically operated devices, each of said devices receiving power from a common set of power distribution lines, comprising:

a central computer including signal generating means and signal receiving means;

central computer data link means coupling said central computer signal generating means and said central computer signal receiving means to said power distribution lines to permit said central computer to send signals over said power distribution lines and to receive signals over said power distribution lines;

said signals from said central computer having a time structure including a portion representative of a particular one of said remote devices with which communication is desired; and

a corresponding plurality of subassemblies associated with said remote devices, each of said subassemblies comprising;

a sensor having signal receiving means responsive to said signals from said central computer and having signal generating means for generating signals representative of desired operation information, said sensor having means for transmitting said signals representative of operation information only in response to a signal from said central computer designating the particular device associated with that particular sensor;

sensor data link means coupling said sensor signal generating means and said sensor signal receiving means to said power distribution lines to permit said sensor to receive said signals from said central computer over said power distribution lines, and to permit said sensor to send said signals representative of operation information to said central computer over said power distribution lines to said central computer, said sensor data link means including

a locally controlled clock for generating a first cyclical pulse train at a carrier frequency, said clock having a phase control input and means for stepping the phase of said first cyclical pulse train by predetermined increments in response to signals at said phase control input,

transmitting means responsive to said first cyclical pulse train for applying a first sinusoidal signal to said power distribution lines, said first sinusoidal signal having said carrier frequency and being in a constant phase relationship with said first cyclical pulse train,

receiving means responsive to a second sinusoidal signal generally at said carrier frequency appearing on said power distribution lines, said receiving means having means for generating a second cyclical pulse train at the frequency of said second sinusoidal signal and in a predetermined phase relationship with respect to said second sinusoidal signal, and

phase comparison means responsive to said first cyclical pulse train from said clock and said second cyclical pulse train from said receiving means, said phase comparison means having means for producing a signal representative of the phase relationship between said first and second cyclical pulse trains;

said sensor signal receiving means and signal generating means together including

first means for applying signals to said phase control input on said clock to step the phase of said first cyclical pulse train by predetermined intervals to represent binary data bits to be transmitted, and

second means for applying signals to said phase control input of said clock to step the phase of said first cyclical waveform by said predetermined increments to bring said first cyclical pulse train generally into a predetermined phase relationship with said second cyclical pulse train during an initial period of data reception in order to permit said phase comparison means to be sensitive to subsequent phase shifts of said predetermined intervals in said second sinusoidal signal, said second means for applying signals operating during data reception only until said first cyclical waveform has been brought into said predetermined phase relationship with said second cyclical waveform;

said sensor having means for transmitting said signals representative of operation information only in response to a signal from said central computer designating the particular device associated with that particular sensor.

2. The invention of claim 1 wherein said electrically operated devices are slot machines, and wherein said sensor includes means for detecting coin drop, coin payout, and wheel rotation.

3. In a communications system for interchanging data among members of a plurality of remote electrically operated devices, each of said devices receiving power from a common set of power distribution lines, an improved data link assembly comprising:

locally controlled clock means for generating a first cyclical waveform at a carrier frequency;

transmitter means for applying said first cyclical waveform to said power distribution lines;

phase shifting means for stepping the phase of said first cyclical waveform by predetermined increments in response to signals at a control input;

transmission control means for providing signals at said control input to cause phase shifts of predetermined intervals representative of binary data to be impressed on said first cyclical waveform;

means for receiving a second cyclical waveform at a frequency approximately the same as said carrier frequency appearing on said power distribution lines;

phase comparison means responsive to the phase relationship between said first and second cyclical waveforms; and

synchronization control means for providing signals at said control input to step the phase of said first cyclical waveform by said predetermined increments in order to bring said first cyclical waveform generally into a predetermined phase relationship with said second cyclical waveform during an initial period of data reception, whereupon subsequent phase shifts of said predetermined intervals in said second cyclical waveform representative of binary data may be detected, said synchronization control means operating during data reception only until said first cyclical waveform has been brought into said predetermined phase relationship with said second cyclical waveform.

4. The invention of claim 3 wherein said predetermined increments are 90°

increments.

5. The invention of claim 3 wherein said transmission control means and said synchronization control means together comprise a programmed microprocessor having first output means operatively coupled to said clock means for generating a cyclical pulse train at a harmonic of said carrier frequency to define said carrier frequency and second output means operatively coupled to said control input.

6. The invention of claim 3 wherein said transmission control means and said phase shifting means are operative to effect 180°

phase shifts of said first cyclical waveform to correspond to bit changes in said data.

7. The invention of claim 3 wherein said phase comparison means comprises:

means for generating a voltage level representative of the duty cycle of the logical exclusive OR between said first and second cyclical waveforms;

threshold means for generating a logic level corresponding to said voltage level; and

window means for generating a logic level indicative of whether or not said voltage level is representative of a duty cycle generally near 50% corresponding to a phase difference generally near ±

90°

.

8. In a communication system for interchanging data among members of a plurality of remote electrically operated devices, each of said devices receiving power from a common set of power distribution lines, an improved data link assembly comprising:

(a) a data link including;

a clock for generating a first cyclical pulse train, said clock having a phase control input and means for varying the phase of said first cyclical pulse train in response to signals at said phase control input;

transmitting means responsive to said first cyclical pulse train for applying a first carrier signal to said power distribution lines, said first carrier signal having a carrier frequency and being in a constant phase relationship with said first cyclical pulse train;

receiving means responsive to a second carrier signal generally at said carrier frequency appearing on said power distribution lines, said receiving means having means for generating a second cyclical pulse train at the frequency of said second carrier signal and in a constant phase relationship with said second carrier signal; and

phase comparison means responsive to said first cyclical pulse train from said clock and said second cyclical pulse train from said receiving means, said phase comparison means having means for producing a signal representative of the phase relationship between said first and second cyclical pulse trains;

(b) signal receiving means and signal generating means together including;

first means for applying signals to said phase control input on said clock to shift the phase of said first cyclical pulse train by 180°

to represent binary data bits to be transmitted; and

second means for applying signals to said phase control input of said clock to step said phase by 90°

increments to bring said first cyclical pulse train into a predetermined phase relationship with said second cyclical pulse train during an initial period of data reception in order to permit said phase comparison means to be rendered sensitive to subsequent 180°

phase shifts in said second carrier signal, said second means for applying signals operating during data reception only until said first cyclical waveform has been brought into said predetermined phase relationship with said second cyclical waveform.

9. A system for communication between a central computer and at least one remote electrically operated device, said device receiving power from a set of power distribution lines, comprising:

means associated with said central computer for sending a polling message on said power distribution line, said polling message having a time structure including a preamble at a carrier frequency followed by binary data represented by phase shifts relative to said preamble;

a data link associated with said remote electrically operated device comprising;

locally controlled clock means for generating a first cyclical waveform at a frequency close to said carrier frequency;

transmitter means for applying said first cyclical waveform to said power distribution lines;

phase shifting means for stepping the phase of said first cyclical waveform by predetermined increments in response to signals at a control input,

transmission control means for providing signals at said control input to cause phase shifts of predetermined intervals representative of binary data to be impressed on said first cyclical waveform,

means for receiving a second cyclical waveform at approximately said carrier frequency appearing on said power distribution lines,

phase comparison means responsive to the phase relationship between said first and second cyclical waveforms, and

synchronization control means for providing signals at said control input to step the phase of said first cyclical waveform in order to bring said first cyclical waveform generally into a predetermined phase relationship with said second cyclical waveform during an initial period of data reception, whereupon subsequent phase shifts of said predetermined intervals in said second cyclical waveform representative of binary data may be detected, said synchronization control means operating during data reception only until said first cyclical waveform has been brought into said predetermined phase relationship with said second cyclical waveform;

said data link thus being operable initially to synchronize with said preamble, then to demodulate said data portion of said polling message, and finally to transmit a response on said power distribution lines.

10. The invention of claim 9 wherein said phase shifting means comprises means for stepping the phase by 90°

increments.

11. The invention of claim 9 wherein said transmission control means and said synchronization control means together comprise a programmed microprocessor having first output means operatively coupled to said clock means for generating a cyclical pulse train at a harmonic of said carrier frequency to define said carrier frequency and second output means operatively coupled to said control input.

12. The invention of claim 9 wherein said transmission control means and said phase shifting means are operative to effect 180°

phase shifts of said first cyclical waveform to correspond to bit changes in said data.

13. The invention of claim 9 wherein said phase comparison means comprises:

means for generating a voltage level representative of the duty cycle of the logical exclusive OR between said first and second cyclical waveforms;

threshold means for generating a logic level corresponding to said voltage level; and

window means for generating a logic level indicative of whether or not said voltage level is representative of a duty cycle generally near 50% corresponding to a phase difference generally near ±

90°

.

14. The invention of claim 9 wherein said means associated with said central computer comprises a second data link having the claimed elements of said first-mentioned data link of claim 9.