Control System

Pen recorders

Recoders are device used to record and store data into paper or any other reading device. Industrial recorders monitor the changes over time in process measurement signals, and provide a permanent record of those changes. functions can be classified into measuring, processing and recording. In self-balancing recorders, measuring and recording are mainly accomplished by servomechanisms.


Pen recorder:


A typical pen recorder is shown above. The measurement signal, after amplification corresponding to a pre-set measurement range, is converted to a digital signal by an integration type A/D converter.


The converted signal undergoes linearizing and alarm processing in the operation control block, and is then
temporarily stored as display data in memory (RAM) . It is subsequently converted to recording data compatible with the recording equipment.


The recording data is converted back to analog data by a D/A converter and it is sent to the servo amplifier, where it is compared with the pen position signal obtained from the pen-position feedback element. The deviation (error) output is power-amplified by the motor control IC and drives the servomotor.


The position feedback element is an ultrasonic displacement detector, and has no mechanical joints. The servomotor is a thin type brushless DC motor. These components make up a highly reliable contact- free servo system. List printing and scheduled printing of logs is done by a small X- Y plotter that operates independently of the servomechanism. The plotter is controlled by a dedicated one-chip microprocessor.






Instrumentation Engineer

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