Abstract: A pattern processing system associates image input patterns with desired response codes. The image input is stored in an image buffer as an addressable array of sample values. An address sequencer provides a sequence of addresses (or "address stream") to the image buffer and to a response memory. The next address provided by the address sequencer is based upon the current address and the state of the sample value stored in the image buffer at the location corresponding to the current address. Once the address sequencer repeats an address, the address stream is in a repetitive address loop as long as the image stored in the image buffer remains constant. The address loop continues to be generated, since the address sequencer always produces the same next address based upon the same current address and the same sample value stored at that current address.

Abstract: A pattern processing system associates image input patterns with desired response codes. The image input is stored in an image buffer as an addressable array of sample values. An address sequencer provides an address stream containing a plurality of interleaved sequences of addresses to the image buffer and to a read/write response memory. The next address of each sequence provided by the address sequencer is based upon the current address of that sequence and the state of the sample value stored in the image buffer at the location corresponding to the current address. Once the address sequencer repeats an address in a sequence, that address sequence is in a repetitive address loop as long as the image stored in the image buffer remains constant. The address loop continues to be generated, since the address sequencer always produces the same next address for that sequence based upon the same current address and the same sample value stored at that current address.

Abstract: A multiplexed circuit for selecting one of a plurality of vertically spaced resistance temperature devices (RTDs) in a fluid storage tank. An electronic multiplexer is used to select a particular one of a plurality of vertically spaced RTDs to be connected to circuitry for reading the output value of same. The device is used in connection with an intelligent field interface device (FID) at the tank. The FID contains a table storing values for expected ranges of output values from the RTDs. When a value actually read is out of range, the FID causes the multiplexer to select another RTD for reading. The arrangement also allows reading of temperatures at various levels within the tank, irrespective of the actual fluid level.

Abstract: Apparatus for operating a motor driven device and testing the state of a limit switch in series with the motor, in the environment of a field interface device in a tank farm is disclosed. During operation of a relatively high power relay (115), a latched (145) signal ties one side (130) of the two-wire circuit to ground through a low impedance (139). When testing of the state of a series limit switch (119) is needed, the same supply voltage is switched onto one side of the two-wire circuit (147) but the low side of the two-wire circuit is grounded through a relatively high impedance (135, 136) to prevent sufficient current for operating the relay coil (117) from flowing. The presence or absence of current through the high impedance is detected through a coupling device (137) which provides a logical one or zero on an output line (68) to determine whether the limit switch is open or closed.

Abstract: An intelligent field interface device for use in a fluid storage facility is disclosed. A bidirectional standard serial communication bus (20) provides communication between a plurality of the interface devices (17) and a central location (18). Surge and lightning protection (50, 51) as well as a high degree of electrical and magnetic isolation (45) are provided between the power supplies of the system. Each device includes a local one chip microcomputer (35) which has a field set address (56) and communicates through optoisolation (27) with the bus through a UART (28). Analog multiplexing (40) of RTD outputs (176-179) or outputs of other transducers (162) is provided to a local to analog to digital converter (36) so that all measured tank parameters may be transmitted digitally back to the control location. An arrangement for both testing and operating a motor operated valve (110) through a two-wire circuit (141, 132) including a limit switch (119) is also shown.

Abstract: A method for detecting the end point of etching wafers and the like by reflective means. Typically, a detected reflectance signal will have a threshold level representing a lack of substantial etching, a dip in the threshold level representing the commencement of etching and an inflection level representing a maximum rate of light amplitude change. The present method involves subtracting the inflection level from the threshold level and taking a predetermined fraction of the resultant level to define a second threshold level further in the etch cycle which anticipates the end of the cycle. By observational experience, the predetermined fraction can be determined. As soon as the second threshold level is reached, brakes are applied to the etching process so that etching will cease shortly after the predetermined level has been identified.