Function Blocks UM353-1B
April 2012
3-72
3.2.68 PID - PID Controller
PID is a proportional + integral controller and one of five
controller types that can be used on a one per loop basis. It
uses external feedback to provide integral action. The
block allows interaction with other function blocks or
external devices, such as pneumatic controllers and shutoff
switches, to eliminate the windup that can occur with other
controller types. Derivative action is provided when the
parameter TD is non-zero. The controller includes an
autotune feature that can be initiated from the operator
faceplate using the QUICK access feature.
When input A is high (1) the controller operates in the
normal auto mode and when low (0) causes reset R to track
(F-GE). This will force the controller output to track the
feedback within the controller limits and allow the
controller to switch back to auto without bumping the
output.
The process range pointer parameter points to another
function block that has range scaling, such as an analog
input that is the process variable. This enables the
controller to normalize the tuning parameters for the
process range. If this parameter is not configured, the
controller will use a range scaling of 0.00-100.00.
Input I, when changed from low (0) to high (1) or from
high to low, will cause the controller to initialize (i.e.
eliminate any proportional gain action during that cycle).
This can be used to prevent bumping the output when changes are made to the setpoint using a switch block.
POWER UP - During a warm or cold power up, the output will be initialized to MINSCALE and all dynamic
elements will be initialized at the current input on the first scan.
t
D
S
t
D
DG
S
+ 1
+
+
e
+
-
+
A
PG
t
I
S
+ 1
1
O1
F
P
S
BLOCK DIAGRAM
Absolute Value
AE
+
+
+/
-
1
-
A
A
uto
I
nitialize
I
S
etpoint
P
rocess
A
bsolute
E
rror
O
utput
1
F
eedback
Lead
Lag
R
Limit
IN
put units
E
ngineering
-3.3 <
O
< 1 0 3.3%
scaling
IN
put units
E
ngineering
scaling
scaling
inverse scaling
PID Controller
ENG UNITS
.
.
R
an
G
e
P
oin
T
e
R
r3
P
rocess
PID CONTROLLER
DG
DIR
ect
ACT
ing
(H)
................................ NO/YES
(NO)
CONTROLLER
PID
ESN =
000
P
S
F
A
PID
S
etpoint
F
eedback
A
uto
I
NP
U
T
INPUT A
(H)
.......................
loop tag.block tag.output
(null)
E
xec.
S
eq.
N
o.
(H)
............................. 001 to 250
R
T
T
I
S
CA
LE
S
C
A
L
E
I
I
I
N
N
N
P
P
P
U
U
U
T
T
T
P
S
F
S
E
N
INPUT F
(H)
.......................
loop tag.block tag.output (null)
INPUT S
(H)
.......................
loop tag.block tag.output (null)
INPUT P
(H)
.......................
loop tag.block tag.output (null)
MIN
imum
SCALE
(H)
.................................. Real
(0.0)
D
erivative
G
ain
(S)
........................ 1.00 to 30.00
(10.00)
T
ime -
D
erivative
(S)
............. 0.00 to 100.00 min
(0.00)
T
ime -
I
ntegral
(S)
................... 0.001 to 4000 m/r
(100.0)
A
PR
R
an
G
e
P
oin
T
e
R
(S)
....................
loop tag.block tag (null)
AC
T
RI
D
T
D
G
MIN
MAX
ENG
UN I TS
MAX
imum
SCALE
(H)
................................ Real
(100.0)
ENG
ineering
UNITS
(S)
.................6 ASCII Char
(PRCT)
I
I
nitialize
P
roportional
G
ain
(S)
................... 0.001 to 100.0
(1.000)
PG
INPUT I
(H)
........................
loop tag.block tag.output (null)
I
NP
U
T
I
AUTOTUNE
AUTOTUNE
(S)
................................... NO/YES
(YES)
DEV%
% DEV
iation
during Autotune
(S)
.... AUTO, 2.5 to 25.0 (AUTO)
%HYS
% HYS
teresis
during Autotune
(S)
.. AUTO, 0.5 to 10.0
(AUTO)
STEP%
%
output
STEP
on first Autotune
(S)
............ 5% to 40% (10)
AT DYNAM
AT DYNAM
ic settings
(S)
.... Fast, Medium, Slow
(M)
AT RESET
AT RESET
(S)
.................................... NO/YES
(YES)
ATTSOP
POST A
utotune
T
ransfer
(S)
................ NO/YES
(NO)
PPD
D
ecimal
P
oint
P
osition (preferred)
(S)
........... 0.0.0.0.0.0 (0.0)
R
ange
R
O1
O
utput
AE
A
bsolute
E
rror
AW
A
T
W
arning
OR
O
utput
R
ange
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