Control direction – Yokogawa Data Acquisition with PID Control CX2000 User Manual

Page 46

Advertising

1-34

IM 04L31A01-01E

Shutdown Function ON/FF (can be specified only during manual mode using 4- to 20-
mA current output)

The shutdown function closes the control value fully (set the output to 0) exceeding the
dead band of the control valve positioner. When this function is turned ON, the control
output is set to 0 mA if the manual control output becomes –5.0%.

Manipulated

output

20.0 mA

–5.0%

100.0%

Output
display value

3.2 mA

4.0 mA

0.0 mA

Note

The “output high-limit alarm” is not activated even if the control output becomes 0 mA due to

shutdown.

Manual Reset Value (valid only when the integral action is Off)

The manual reset value is the output value when the PV is equal to the SP. For example, if
the manual reset value is set to 50%, the output value is set to 50% when PV = SP.
Selectable range of manual reset value: –5.0 to 105.0%

Control Direction

The control action direction defines the direction (increase or decrease) in which the
control output value changes according to the polarity of the deviation between the SP
and the PV. In reverse action (factory default setting), the control output value
decreases when the PV is greater than the SP and vice versa. The control output is
varied using direct control or reverse control specified beforehand in sync with the
deviation between the SP and the PV at that point. Direct action and reverse action can
be switched in the middle of operation.

Condition

ON/OFF output

Current output

PV time-proportional
output

Output change direction
for the 4-20 mA case

PV>SP

OFF

Current decrease

ON time decrease

Reverse action

Direct action

Minimum value

(PV is low)

Maximum value

(PV is high)

4mA

20 mA

PV<SP

Current increase

ON time increase