Abstract: An interface selector connecting a plurality of field digital devices to a single digital receiving device is disclosed. The interface selector provides a means for the digital receiving device to select which field digital device is to transmit valid data. Circuitry is provided to disable all other field digital devices. Signal lines are provided for the digital receiving device to verify that only one field digital device is transmitting data. Circuitry is also provided to prevent transmission of data if all field digital devices are selected simultaneously.

Abstract: The purpose of this monitor is to detect a failure in either the computer or the monitor itself. The computer supplies an output to the monitor which toggles at a preselected first frequency. The monitor includes a mechanism for sensing if the output of the computer is toggling at a frequency outside a preselected range of frequencies. A test circuit generates periodic test pulses and a clock circuit generates timing pulses. A latching mechanism changes from a first state to a second state in response to the sensing mechanism sensing that the first frequency of the computer is outside said preselected range. A bistable mechanism is coupled to the latching mechanism and generates a second frequency only if the latch mechanism is in its first state and if the test pulses and timing pulses are present at the bistable mechanism. The failure of the monitor to generate the second frequency indicates a failure of the computer or the monitor.

Abstract: An improved system and method is disclosed for compounding batches of a plurality of constituents in accordance with a predetermined formula. The individual batch constituents are sequentially fed into a batch receiving hopper. Feeding of each constituent is controlled in response to the current weight of the constituent in the hopper and the current rate at which the constituent is being fed. Preferably, feeding is accomplished at a plurality of decreasing rates with the fastest rate maintained for a maximum time to minimize the total time required to compound the batch.