Synchronizing controllers linked by a communications network
First Claim
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1. A system for synchronizing controllers comprising:
- a first controller for incrementing a master count of ticks produced at periodic intervals, and for executing event information when the master tick count matches a target tick count;
a second controller for adjusting, with reference to the master tick count, a incremented shadow tick count of ticks produced at periodic intervals, and for executing second event information when the shadow tick count matches the target tick count, the executions by said first and second controllers being mutually synchronized; and
a communications network interconnecting said first and second controllers.
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Abstract
A control system includes controllers that are coupled mutually by a communications network, on which information, transmitted from a master controller to a slave controller, is used to make timing corrections on the slave controller in order to synchronize event timers on the slave controller with that of the master controller. Timing accuracy for the occurrence of the event commanded by each controller is synchronized in narrow range of time, preferably within a few milliseconds depending on the specific application and system.
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Citations
20 Claims
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1. A system for synchronizing controllers comprising:
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a first controller for incrementing a master count of ticks produced at periodic intervals, and for executing event information when the master tick count matches a target tick count;
a second controller for adjusting, with reference to the master tick count, a incremented shadow tick count of ticks produced at periodic intervals, and for executing second event information when the shadow tick count matches the target tick count, the executions by said first and second controllers being mutually synchronized; and
a communications network interconnecting said first and second controllers. - View Dependent Claims (2, 3, 4, 5, 6)
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7. In a system of intercommunicating controllers, a method for synchronizing the occurrence of an event on each controller, the method comprising the steps of:
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a. maintaining on a master controller a count of ticks produced by a first clock;
b. sending an inquiry from a slave controller to the master controller for the tick count on the master controller;
c. sending a response from the master controller to the slave controller that includes the tick count on the master controller;
d. adjusting a shadow tick count on the slave controller on the basis of the tick count sent from the master controller;
e. incrementing the shadow tick count on the slave controller when ticks are produced by a second clock;
f. establishing a target tick count at which an event is to occur on the master controller and a target shadow tick count at which an event is to occur on the slave controller;
g. using the master controller to command an event when the tick count matches the target tick count; and
h. using the slave controller to command an event when the shadow tick count matches the target shadow tick count. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for synchronizing events produced by multiple controllers, the method comprising the steps of:
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a. connecting a master controller to a communications network;
b. connecting a slave controller to the communications network;
c. synchronizing an incremented tick count on each controller using the communications network;
d. determining a target tick count on each controller at which an event is to occur;
e. preparing event information on the master controller and slave controller to be executed at the next event; and
f. executing the respective event information on the master controller and slave controller when the tick count on the respective controller matches the target tick count. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification