Leeds & Northrup Company

Samuel A Arcara

Howard S Hoopes

Paul Anderson

A P-I-D controller in a process control system is self tuned in response to discrete time model identification parameters which are converted to P-I-D form. Additionally, the P-I-D parameters are limited to prevent them from exceeding the controller's specified range.

Self tuning of P-I-D controller by conversion of discrete time model

Unwanted bias is eliminated from a process control system by high pass filters which are disposed between the process and the process model.

Filter arrangement for elimination of unwanted bias in a model reference

A circuit for preventing data transfers to a RAM by a microprocessor when primary ac power fails also puts the RAM in standby after a period adequate to complete any data transfer started. The sequence is provided by providing a first signal to the microprocessor transfer enable line upon loss of primary power. A second signal is provided for the enable line of the RAM after a predetermined delay but before decay of the dc power to the RAM.

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Telford, PA, United States of America

Samuel A Arcara