Abstract: A data monitoring system is provided which is coupled to a data bus and which responds to identified data to cause the display of data from one or more designated sensors. The system can also provide outputs to activate and deactive relays and to control other devices. The programming and operation of a master controller does not have to be altered for use of the present system. The system operates to monitor one or more designated sensors and data from such sensors and to utilize the received data for display and/or operational purposes. The invention is especially useful in a process control network in which a large number of sensors is distributed throughout a facility and in which it is desirable to be able to read sensor data from one or more remote locations within a facility. The invention is also useful for other circumstances wherein data on a bus is to be monitored at a remote position.