Fisher FIELDVUE DVC6200p Instruction Manual page 72

Principle of Operation
June 2017
(output A is not available). With relay C an increasing setpoint will produce an increasing pressure on output A (output
B is not available). The output A pressure is used for double‐acting and single‐acting direct applications. The output B
pressure is used for double‐acting and single‐acting reverse applications.
Figure A‐2. FIELDVUE DVC6200p Digital Valve Controller Assembly
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As shown in figure A‐1, the increased output A pressure causes the actuator stem to move upward. The stem position
is sensed by the travel sensor. The stem continues to move upward until the correct stem position is attained. At this
point the printed wiring board assembly stabilizes the I/P drive signal. This prevents any further increase in the
pneumatic signal from the I/P converter.
As the digital setpoint decreases, the drive signal to the I/P converter submodule decreases, decreasing the I/P output
pressure. The pneumatic relay decreases the output A pressure and increases the output B pressure. The stem moves
downward until the correct position is attained. At this point the printed wiring board assembly stabilizes the I/P drive
signal. This prevents any decrease in the pneumatic signal from the I/P converter.
70
PRINTED WIRING
BOARD ASSEMBLY
MODULE BASE ASSEMBLY
PNEUMATIC RELAY
I/P CONVERTER
Instruction Manual
D103563X012
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