Abstract: A system for controlling a plurality of loads based upon command and residual priorities having a plurality of loads, a controller for controlling the loads according to at least two programs, each program having a command priority used for a program which wants control of a load and a residual priority retained for the program having control, the controller comparing the command priority of the program wanting control of the load to the residual priority of the program having control for thereby providing a command instruction to the load if the command priority of the program wanting control is greater than or equal to the residual priority of the program having control, and a communication channel connected between the controller and the loads for communicating the command instruction to the load.

Abstract: A transceiver circuit for connecting a data processing unit to a communication bus, wherein said data processing unit is capable of transmitting, receiving and processing non-return to zero (NRZ) signals having a normally high level and assuming a low level to indicate a data bit and said communication bus is capable of transmitting a pulse-no pulse signal to indicate data bits, is disclosed having an input connected to the data processing unit for receiving the non-return to zero signals, a triggering circuit which is responsive to a leading edge of a non-return to zero signal to supply triggering pulses having a predetermined frequency, a gating circuit for passing through the triggering pulses as long as the non-return to zero signal is at a predetermined level, and a pulse-no pulse circuit responsive to the triggering pulses for supplying the pulse-no pulse signals to the communication bus.

Abstract: A protocol system for data processing equipment, particularly equipment used in building automation monitoring and control systems for air-conditioning control and monitoring of fire and security points is disclosed having a plurality of stations connected to a data bus, each station having an apparatus for monitoring the traffic on the data bus, calculating its turn to transmit or time slot during which it is permitted to transmit data on the bus and updating its calculated turn or time slot after each station designated to transmit in a turn or time slot after each station designated to transmit in a turn before it has transmitted data. Although each station has a designated time slot during which it may transmit, each time slot is of variable duration depending upon the extent of data to be transmitted.