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Asynchronous Attachment of Timed Data Inputs

IP.com Disclosure Number: IPCOM000049856D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 36K

Publishing Venue

IBM

Related People

Leggate, JW: AUTHOR

Abstract

A technique of computer sampling of asynchronously transmitted byte sequential data is illustrated in the above figure. The method assures input of valid data when the computer has a maximum sampling rate only slightly exceeding the asynchronous digit transfer input rates and the computer misses one or more input digits (or a whole sequence of digits) when interrupted to perform higher priority functions. In particular, environmental digital inputs such as temperature or humidity, are read to the computer. As shown in the above figure, the computer compresses the input data to eliminate invalid input data and redundant 8-bit bytes, and then checks to see that each group of four numbers representative of a meter reading has a proper sequence.

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Asynchronous Attachment of Timed Data Inputs

A technique of computer sampling of asynchronously transmitted byte sequential data is illustrated in the above figure. The method assures input of valid data when the computer has a maximum sampling rate only slightly exceeding the asynchronous digit transfer input rates and the computer misses one or more input digits (or a whole sequence of digits) when interrupted to perform higher priority functions. In particular, environmental digital inputs such as temperature or humidity, are read to the computer. As shown in the above figure, the computer compresses the input data to eliminate invalid input data and redundant 8-bit bytes, and then checks to see that each group of four numbers representative of a meter reading has a proper sequence. Finally, the computer checks to see if each proper sequence that should represent a meter reading is consistent with previous meter readings.

The temperature or humidity meter readings are timed independently of the computer and each reading in the present example contains four decimal digits, each decimal digit being sent to the computer as an 8-bit binary word. The binary word includes an identifier for the position of the digit in the meter reading and the binary value for the decimal digit. This position identifier has a valid value only when the corresponding decimal digit is valid on the meter digital output lines.

Examples of a meter reading output are shown in Table 1. Each decimal digit has an assigned digit position identifier N(1) - N (4).

There are six readings at times T(1) - T(6) in Table I. Each reading is transmitted to the computer in sequence N(1) , N(3), N(2), N(4) for each time sample T(1) - T(6) from the meter. This sequence is shown in Table II.

When the computer reads the transmitted sequences, it may sample each digit N(1) - N(4) more than once during a given sampling period T from the meter. In addition, the computer may be interrupted and miss a portion of the reading during a sample period T. Table III shows a ty...