Controller for use in an environment control network capable of storing diagnostic information

A VAV controller operatively associated with a VAV box, said VAV controller coupled to a first communication bus, said VAV controller comprising:

• parameter input means for receiving a parameter value from a sensor;
• a communication port coupled with said first communication bus;
• memory means for storing diagnostic information;
• and
• processor means coupled with said memory means, said parameter input means, and said communication port, for generating said diagnostic information and receiving said parameter value, and said processor means programmed to receive said parameter value at said parameter input said processor means programmed to calculate said diagnostic information and store in said memory said diagnostic information related to an average error associated with said parameter value said processor means programmed to provide said diagnostic information to said communication port, wherein a computer is coupled to said communication port via said first communication bus and said computer receives said diagnostic information, and wherein said controller provides an actuator signal to said VAV box for controlling air flow, and wherein said diagnostic information further is comprised of a plurality of samples of said actuator signal.