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Dual Mode Analog Output for Direct Digital Control

IP.com Disclosure Number: IPCOM000093132D
Original Publication Date: 1967-May-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Oswald, RK: AUTHOR

Abstract

In direct digital control, the value of the manipulated variable provided by the analog output device can be updated. This is effected by furnishing either the full value of the new output or the incremental change from the previous output. This device can operate individual channels in either mode by computer control of switch 10.

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Dual Mode Analog Output for Direct Digital Control

In direct digital control, the value of the manipulated variable provided by the analog output device can be updated. This is effected by furnishing either the full value of the new output or the incremental change from the previous output. This device can operate individual channels in either mode by computer control of switch 10.

When switch 10 is connected to terminal 12, a manipulated variable, e.g., pressure, temperature, etc., is being updated in a proportional, full value manner. A signal is made available from digital-to-analog converter 14 to amplifier 16. A first channel, identified by switch 18 and storage capacitor 20, receives a charge value from amplifier 16.

An associated field-effect transistor FET 21 passes a signal onto amplifier 22 having a feedback loop 24. The latter has a manipulated variable actuator 26, e.g., a valve actuator, and current feedback resistor 28. The output of amplifier 22 is returned through switches 30 and 10 to amplifier 16. Thus, control of a variable's value, as represented by the charge on capacitor 20, is implemented in a proportional mode.

When updating a channel in the incremental mode, switch 10 is transferred to contact 32. Switch 38 is first closed and capacitor 36 charged to the present value of output by unity gain amplifier 34.

With the desired increment value in DAC 14, switch 38 is opened and switch 18 closed updating the output to the desired new value.

This...