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Browse Prior Art Database

Checking Means for Analog Input Subsystems

IP.com Disclosure Number: IPCOM000077292D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Utley, BG: AUTHOR

Abstract

Various components in an analog input subsystem are tested. The proper functioning of double or single-pole, single-throw type switching functions in a multiplexer, analog amplifier operation, analog-to-digital converter operation and the condition of the analog sources can be selectively tested. The operation is similar to that discussed in patent 3,653,03?.

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Checking Means for Analog Input Subsystems

Various components in an analog input subsystem are tested. The proper functioning of double or single-pole, single-throw type switching functions in a multiplexer, analog amplifier operation, analog-to-digital converter operation and the condition of the analog sources can be selectively tested. The operation is similar to that discussed in patent 3,653,03?.

With switches 303 open, switch 307 is closed applying the output of the digital-to-analog-converter D/A 117 to the input of amplifier 109. The output of 109 is coupled to analog-to-digital converter 111 via 149. If 109 and 111 are operating properly, the result of the conversion as present on 133 will be within acceptable tolerance of the original number supplied to D/A register 115 through lines 123. As a result, computer 121 receives a signal from comparator 119 from line 139 indicating that 109 and 111 are operating correctly.

In a second mode of operation, switch 307 and one of switches 303 are closed simultaneously. If the selected switch 303 is operating properly and the analog source 301 connected to it is not open, the voltage input to amplifier 109 will be at an intermediate level between the D/A 117 output and the analog source 301 voltage. This condition can be determined by 121 as a result of knowing the ADC output on line 133, 137 and the D/A input on line 123. If switch 303 is not closing properly or the selected analog source 301 is open, the full D/A...