GE VersaMax PLC, Руководство пользователя

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14.1 Operands of the PID Function
The PID function compares feedback from
a process variable (PV) with a desired
process set point (SP) and updates a
control variable (CV) based on the error.
The PID function uses PID loop gains and
other parameters stored in a 40-word
reference array of 16-bit integer words to
solve the PID algorithm at the desired time
interval.
14.1.1 Parameters of the PID Function Block
Para-meter
Description Allowed Types Allowed Operands Optional
Address
(????)
Location of the PID reference array,
which contains user-configurable and
internal parameters, described in the
section, Reference Array Parameters
later in this chapter. Uses 40 words that
cannot be shared.
WORD
R, L, P, W and
symbolic
No
SP
The control loop or process set point.
Set using process variable counts, the
PID function adjusts the output control
variable so that the process variable
matches the set point (zero error).
INT, BOOL array of
length 16 or more
All except S, SA,
SB, and SC
No
PV
Process Variable input from the process
being controlled. Often a %AI input.
INT, BOOL array of
length 16 or more
All except S, SA,
SB, and SC, and
constant
No
MAN
When energized to 1 (through a
contact), the PID function block is in
manual mode. If this input is 0, the PID
function block is in automatic mode.
NA Flow No
UP
If energized along with MAN, increases
the control variable by 1 CV count per
solution of the PID function.
NA Flow No
DN
If energized along with MAN, decreases
the control variable by 1 CV count per
solution of the PID function.
NA Flow No
CV
The control variable output to the
process. Often a %AQ output.
INT, BOOL array of
length 16 or more
All except %S and
constant
No
274 GFK-1503E VersaMax PLC User Manual
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