A data collection system wherein a central or data collection station is interconnected through data transmission lines with a plurality of meters or terminal stations at remote places and prior to the data reading operation a high-level voltage is applied from the central station to charge the stray capacitance between the data transmission lines and ground and thereafter a predetermined voltage is applied for reading data.

A data transmission system for individually sensing a plurality of remote signal sources and interconnecting the selected signal source with one or more signal destinations by switch means at each signal source and at each signal destination.

The present invention is directed to a read only memory, wherein the preferred embodiment provides an analog read only memory using charge coupled devices. Fixed but selectable charge packets are used to charge elements in a charge coupled device array; where selectable charging may be provided by selecting resistor values, selecting capacitor values, selectable masking of photo detectors, and other such methods. The accumulated fixed packets of charge are then shifted with a charge coupled device register to provide sequential analog signal outputs. Use of an analog read only memory permits hybrid signal processing such as for voice response. Use of a serial output simplifies the accessing and reduces accessing electronics by eliminating the more complex random access arrangements. The analog read only memory of the present invention has the additional advantage of being a non-volatile memory for preserving stored information when power is removed; where conventional charge coupled device memories are volatile and lose all stored information when power is removed. The analog read only memory of the present invention is particularly useful in systems for generating analog output signals such as voice response systems and filtering systems. Accessing of analog samples from the read only memory can be controlled with a digital processor such as by controlling shifting of the charge couple device shift register and by selecting the desired output information under digital control.

A sensor connection apparatus for connecting a plurality of sensors to a process controller having a bus for transferring information, wherein each sensor produces an output corresponding to a sensed condition, includes a respective sensor cable that can be connected at one end to each sensor; a concentrator having each of the sensor cables connected thereto; the concentrator being connected to the bus; the concentrator comprising a circuit for producing for each sensor and associated sensor cable connected thereto a first signal in response to the sensor output and a second signal that corresponds to a sensor cable condition; the circuit further operating to couple the first and second signals for each sensor connected to the concentrator onto the bus for access by the process controller. In one embodiment, the concentrator transmits data to the process controller using a standardized communications protocol, such as CAN, using a microcontroller and transceiver.

A monitor/control communication net with intelligent peripherals, that is, peripherals which are capable of monitoring and/or controlling various devices in accordance with messages received from a central panel cpu and which are also capable of reporting to the central panel the status of one or more devices monitored by the peripheral. Each peripheral is assigned a unique address by which it is polled by the central panel. All communication messages between the central panel and peripherals include a format code which indicates the nature of the message and the length of any data field in the message. Communication time is minimized by permitting the data field to vary in length from one peripheral to another, depending on the number and type of devices being monitored and/or controlled by the peripherals.