System recovery in a heating, ventilation and air conditioning network
First Claim
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1. A method of using a heartbeat in an HVAC network that includes a first subnet controller and a second subnet controller on a subnet, comprising:
- said first subnet controller providing a heartbeat message via said network;
said second subnet controller in an inactive state determining if said first subnet controller has provided said heartbeat message within a first specified time period;
said second subnet controller remaining in said inactive state in the event that said first subnet controller provides said heartbeat message within said first specified time period;
said second subnet controller switching to an active state in the event that said first subnet controller does not provide said heartbeat message within said first specified time period; and
a device on said subnet determining the presence or absence of said heartbeat within a second specified time period;
wherein;
in the event that said device detects said heartbeat message within said second specified time period, said device continues to operate in a prior mode; and
in the event that said device fails to detect said heartbeat message within said second specified time period, said devicea) issues a heartbeat-message-missing alarm;
b) ceases to operate in a communication mode; and
c) continues to generate device status messages via said subnet.
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Abstract
The disclosure provides various embodiments of systems and methods of generating a heartbeat in an HVAC system and networks. In an embodiment, a method includes a heartbeat message being sent by a first subnet controller upon the first subnet controller taking active control of a subnet of the HVAC network. The active heartbeat message timer is reset. Another heartbeat message is sent if a specified amount of time has elapsed since a previous heartbeat message was sent by said heartbeat generator.
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Citations
14 Claims
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1. A method of using a heartbeat in an HVAC network that includes a first subnet controller and a second subnet controller on a subnet, comprising:
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said first subnet controller providing a heartbeat message via said network; said second subnet controller in an inactive state determining if said first subnet controller has provided said heartbeat message within a first specified time period; said second subnet controller remaining in said inactive state in the event that said first subnet controller provides said heartbeat message within said first specified time period; said second subnet controller switching to an active state in the event that said first subnet controller does not provide said heartbeat message within said first specified time period; and a device on said subnet determining the presence or absence of said heartbeat within a second specified time period;
wherein;in the event that said device detects said heartbeat message within said second specified time period, said device continues to operate in a prior mode; and in the event that said device fails to detect said heartbeat message within said second specified time period, said device a) issues a heartbeat-message-missing alarm; b) ceases to operate in a communication mode; and c) continues to generate device status messages via said subnet. - View Dependent Claims (2, 3, 4)
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5. An HVAC network, comprising:
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a first subnet controller on a subnet of said HVAC network, said first subnet controller being configured to periodically send a heartbeat message over said network; and a second subnet controller on said subnet, said second subnet controller being configured to determine if said first subnet controller has provided said heartbeat message within a first specified time period; a device on said subnet configured to determine the presence or absence of said heartbeat within a second specified time period;
wherein;in the event that said device detects said heartbeat message within said second specified time period, said device continues to operate in a prior mode; and in the event that said device fails to detect said heartbeat message within said second specified time period, said device a) issues a heartbeat-message-missing alarm; b) ceases to operate in a communication mode; and c) continues to generate device status messages via said subnet. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification