This invention relates to the programmed control of heating and cooling systems utilizing one or more programmed microprocessors. In particular, this invention relates to the manner in which the programmed control in the microprocessors interfaces with various elements in the heating and cooling systems.
U.S. patent application Ser. No. 08/143,029, now U.S. Pat. No. 5,491,649, entitled, "Configuration Control for HVAC Systems" filed in the names of Arthur Friday, Jr., Chi-Pin Chan and Brett Desmarais discloses a programmed microprocessor control system having separate hardware and software interfaces. The hardware interface defines communication channels to the hardware elements of an HVAC system that are to perform heating or cooling functions. The software interface defines a number of software variables present in a control program residing in the microprocessor. Configuration data stored in memory associated with the microprocessor maps at least some of these software variables to the communication channels defined by the hardware interface. Further software utilizes the configuration data so as to allow information to be transferred between the interfaces.
The above transfer of information between the interfaces does not take into account the possibility of erroneous information coming from one of the hardware elements to the hardware interface. In this regard, a particular hardware element may not necessarily be functioning properly or the communication link from the element might be temporarily experiencing difficulty. In either case it may not be advisable to further transfer the communicated value from the hardware interface to the software interface. It may also not be advisable to continue operation in the event of a serious problem having arisen at the hardware control element.