YME Engineering Course

I. REGULATORY CONTROL FUNCTION BLOCKS
value. The direct action and reverse action indicate the increase and
decrease directions of the manipulated output value (MV) corresponding
to deviation changes. When the setpoint value (SV) is fixed, the
relationship between the process value (PV) and the manipulated output
value (MV) in direct action and the reversed action is shown as follows.
• Direct action
The control action in which the manipulated output value (MV)
increases as the process variable (PV) increases, or decreases as
the process variable decreases.
• Reverse action
The control action in which the manipulated output value (MV)
decreases as the process variable (PV) increases, or increases as
the process variable decreases.
♦ Measurement Tracking
The process variable tracking function prevent the abrupt changes in the
manipulated output value (MV) when change from the manual (MAN)
mode to automatic (AUT) mode, by forcing the setpoint value (SV) to
agree with the process variable (PV).
When switching from the manual (MAN) mode to automatic (AUT) mode,
the existence of a large deviation is harmful, since it makes the
manipulated output change very large. If force the setpoint value (SV) to
agree with the process variable (PV) in manual mode operation via
process variable tracking, abrupt Control Action can be avoided when the
mode switches to automatic (AUT).
Suppose a primary loop is in cascade connection and controls in the
automatic (AUT) or cascade (CAS) mode. If the mode of the secondary
loop in the cascade connection switches from cascade (CAS) to automatic
(AUT), the cascade connection becomes open and the control action of
the primary side loop can stop. In this situation, the setpoint value (SV) of
the primary loop can be forced to agree with the process variable (PV) by
the process variable tracking function. Define process variable tracking as
below
• MAN mode: Select “Yes” or “No.”
The default is “No.”
• AUT and CND mode: Select “Yes” or “No.”
The default is “No.”
• CAS and CND mode: Select “Yes” or “No.”
The default is “Yes.”
♦ Output Signal Conversion
The output signal conversion may be used for the processes that are
common to the Regulatory Control Blocks and the Calculation Blocks, and
for the specific function blocks, which have specific output process
function.
YME Training Center I-6
CS3KR3-ENG 1 ST Edition Jan 2002