Patent ID: 8433446

Claim:
An HVAC data processing and communication network, comprising: a system device configured to: receive a control message from a data bus and operate according to a control setting communicated thereby; and generate an alarm message in the event that said device enters an alarm state in response to an alarm condition; a user interface configured to receive said alarm message and display alarm information in response thereto; a subnet controller configured to provide operational control of said system device via said control message, wherein said subnet controller determines said operational control from an operational status of said system device independent of said alarm message; and a local controller, associated with said system device, configured to store a current alarm record associated with said alarm state in a memory, and to replace an oldest alarm record with said current alarm record, wherein said memory includes volatile memory and nonvolatile memory (NVM), with minor alarm records being stored in said volatile memory, and moderate and critical alarms being stored in said NVM.