System and method for terminating a bus
First Claim
1. A system comprising:
- a bus having at least two end points;
first and second sets of devices each containing a quantity of devices from 0 to N, wherein N is any integer greater than 0, and wherein said first and second sets of devices are connected to said bus;
a controller coupled to said bus, configured to discover whether to terminate said bus at one of said end points relative to said first and second sets of devices, dependent upon whether said controller receives a reply message in response to a test message sent to said first and second sets of devices.
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Accused Products
Abstract
An exemplary system includes a bus (such as CAN bus) having at least two end points. A first and/or a second set of an undetermined number of devices may be connected to the bus. A controller is also connected to the bus, and is configured to establish a termination of the bus at one of the end points relative to the first and second sets of devices, dependent upon whether the controller receives a reply message in response to a communication test message sent to the first and second sets of devices at different times. If the controller discovers that devices are connected to the bus in both sets, the controller is relieved of establishing an end point on either end of the bus. Otherwise, if the controller discovers that devices are only connected to the bus in one of the two sets, the controller is therefore, configured to terminate an end of the bus.
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Citations
20 Claims
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1. A system comprising:
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a bus having at least two end points;
first and second sets of devices each containing a quantity of devices from 0 to N, wherein N is any integer greater than 0, and wherein said first and second sets of devices are connected to said bus;
a controller coupled to said bus, configured to discover whether to terminate said bus at one of said end points relative to said first and second sets of devices, dependent upon whether said controller receives a reply message in response to a test message sent to said first and second sets of devices. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of terminating a bus comprising:
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activating a termination load across a controller device;
enabling a first set of potential devices connected to said bus;
attempting to establish communication with any of said first set of potential devices;
deactivating said termination load across said controller device, if communication is established between said controller and at least one of said potential devices in said first set of potential devices;
enabling a second set of potential devices connected to said bus;
attempting to establish communication with any of said second set of potential devices; and
reactivating said termination load across said controller device, if communication is not established between said controller and at least one of said potential devices in said second set of devices. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method of terminating a CAN bus, comprising:
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enabling a first branch of said CAN bus;
establishing a controller as a termination point on said CAN bus by connecting a termination resistor in parallel with said controller;
determining whether there is a device, other than said controller connected to said first branch, by sending a first communication message on said CAN bus and awaiting a reply message;
if a reply message is received, disconnecting said termination resistor from said controller, thereby removing said controller as said termination point on said first branch;
leaving enabled said first branch of said CAN bus;
enabling a second branch of said CAN bus;
determining whether there is a device, other than said controller connected to said second branch, by sending a second communication message on said CAN bus and awaiting a reply message;
if no reply message is received in response to said second communication message, re-establishing said controller as said termination point on said CAN bus by reconnecting said termination resistor in parallel with said controller. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification