Write access security protocol for heating, ventilation, and/or air-conditioning (HVAC) device
The present disclosure includes a heating, ventilation, and/or air-conditioning (HVAC) control system with a controller and a device communicatively coupled to the controller. The device is configured to implement an engagement protocol, wherein to grant the controller write access to protected registers of the device the engagement protocol functions to require: receiving a reset command at a reset register of the device; receiving a passcode at a passcode register of the device; matching the passcode received at the passcode register to an authentication passcode; and receiving or matching the passcode within a timeframe defined by a timer.
1 . A heating, ventilation, and/or air-conditioning (HVAC) control system, comprising:
a controller; and
a device communicatively coupled to the controller and configured to implement an engagement protocol, wherein to grant the controller write access to protected registers of the device the engagement protocol is configured to require:
receiving a reset command from the controller at a reset register of the device;
receiving a passcode from the controller at a passcode register of the device within a timeframe defined by a timer; and
matching the passcode received at the passcode register to an authentication passcode within the timeframe, wherein the authentication passcode is stored in an authentication register of the device, and the authentication register is inaccessible to the controller.
2 . The HVAC control system of claim 1 , wherein the timeframe is measured from a completed reset of the device.
3 . The HVAC control system of claim 1 , wherein the device is configured to implement an implementation protocol, wherein:
to implement changes written to the protected registers of the device after the write access has been granted due to performance of the engagement protocol, the implementation protocol is configured to require receiving an additional reset command at the reset register or a different reset register within an additional timeframe defined by the timer or an additional timer.
4 . The HVAC control system of claim 3 , wherein the device comprises HVAC equipment having a control board that maintains the passcode register as writable whether the protected registers are writable or not.
5 . The HVAC control system of claim 1 , wherein to grant the controller the write access to the protected registers of the device the engagement protocol is configured to require the device to complete a reset in response to the reset command.
6 . The HVAC control system of claim 1 , wherein the engagement protocol is configured to block the write access by maintaining a default and not actively granting the write access.
7 . The HVAC control system of claim 1 , wherein the engagement protocol is configured to block the write access when the passcode is not received at the passcode register and matched with the authentication passcode within an additional timeframe.
8 . The HVAC control system of claim 7 , wherein the additional timeframe is measured from a completed reset of the device.
9 . The HVAC control system of claim 1 , wherein the device comprises an air measurement device.
10 . The HVAC control system of claim 9 , wherein the air measurement device includes the reset register, the passcode register, and the protected registers, and wherein the protected registers are configured to store operational data for the air measurement device.
11 . The HVAC control system of claim 1 , wherein the controller comprises a master control board and the device comprises a sensor communicatively coupled to a device control board.
12 . The HVAC control system of claim 3 , wherein at least a subset of the protected registers are readable by the controller without performing the engagement protocol or the implementation protocol.
13 . A tangible, non-transitory, computer-readable medium storing instructions that, when executed by one or more processors, cause the one or more processors to implement an engagement protocol, wherein to grant a controller write access to protected registers of a device, the engagement protocol is configured to require:
receiving a reset command from the controller at a reset register of the device;
receiving a passcode from the controller at a passcode register of the device within a timeframe defined by a timer; and
matching the passcode received at the passcode register to an authentication passcode within the time frame, wherein the authentication passcode is stored in an authentication register of the device, and the authentication register is inaccessible to the controller.
14 . The tangible, non-transitory, computer-readable medium of claim 13 storing the instructions that, when executed by one or more processors, cause the one or more processors to implement an implementation protocol, wherein:
to implement changes written to the protected registers of the device after the write access has been granted due to performance of the engagement protocol, the implementation protocol is configured to require receiving an additional reset command at the reset register within an additional timeframe defined by the timer or an additional timer.
15 . The tangible, non-transitory, computer-readable medium of claim 13 storing the instructions that, when executed by one or more processors, cause the one or more processors to require the device to complete a reset in response to the reset command before granting the controller the write access to the protected registers of the device.
16 . The tangible, non-transitory, computer-readable medium of claim 13 storing the instructions that, when executed by one or more processors, cause the one or more processors to block the write access when the passcode received at the passcode register does not match the authentication passcode.
17 . A method of operating a heating, ventilation, and air-conditioning (HVAC) control system, comprising:
performing an engagement protocol to control write access to protected registers of a device, wherein operation of the engagement protocol comprises blocking write access to the protected registers until after:
receiving a reset command at a reset register of the device;
completing a reset of the device in response to the reset command;
after completing the reset, receiving a passcode at a passcode register of the device within a timeframe defined by a timer, and
matching the passcode received at the passcode register to an authentication passcode within the timeframe, wherein the authentication passcode is stored in an authentication register of the device, and the authentication register is inaccessible to the controller.
18 . The method of claim 17 , comprising performing an implementation protocol to implement changes written to the protected registers of the device after the write access has been granted due to performance of the engagement protocol, wherein the implementation protocol includes receiving an additional reset command at the reset register within an additional timeframe defined by the timer or an additional timer.
19 . The method of claim 17 , comprising receiving updated write data into the protected registers and implementing previously saved write data after a time period due to lack of an additional reset of the device within the timer period.