Siemens SIMATIC S5-95F - Page 258

Blocks and Their Functions S5-95F
Figure 9-2. Block Diagram of the PID Controller
TI
R
TD
Z
k
-Z
k-1
Sum-
ming
unit
Lim-
iter
OG
UG
a a a
a
a
a
a a a
-
a a a
a
a
a
a a a
+
a a a a
a
a a
a
a
a a
a
a a a a
+
a a a
a
a
a
a
a
a
a a a
+
a a a a
a
a a
a
a
a a
a
a a a a
+
a a a
a
a
a
a
a
a
a a a
+
a a a a
a
a a
a
a
a a
a
a a a a
+
a a a
a
a
a
a
a
a
a a a
0
a a a
a
a
a
a
a
a
a a a
Y
a a a
a
a
a
a a a
0
a a
a a
a a
1
a a a
a
a
a
a
a
a
a a a
1
a a a
a
a
a
a
a
a
a a a
0
a a a a
a
a a
a
a
a a
a
a a a a
dY
a a a a a
a
a a a
a
a a a a a
XW
a a a
a
a
a
a
a
a
a a a
+
a a a
a
a
a
a a a
+
a a a a
a
a a
a
a a a a
dY
YH, dYH
a a a a a a a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a a a a a a a
STEU
Bit 0
BGUG
BGOG
a a a
a
a
a
a a a
0
Z
W
X
XZ
a a a
a
a
a
a a a
1
K
a a a a a a a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a a a a a a a
STEU
Bit 1
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
STEU
Bit 5
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
STEU
Bit 2
Manual
function
a a a a a a a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a a a a a a a
STEU
Bit 3
a a a a a a a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a
a a a a a
a
a a a a a a a
STEU
Bit 4
0
YA,
dYA
a a a
a
a
a
a
a
a
a a a
0
a a a
a a a
a a a
a a a
1
0
a a
a a
a a
1
Table 9-3. Legend for the Block Diagram of the PID Controller (Figure 9-2)
Designation Explanation
K Proportional coefficient: K>0 direct acting
K<0 reverse acting
R R parameter (usually 1000)
TA Scan time
TN
TV
Integral-action time
Derivative-action time
TI Constant TI TI=Scan time TA/Integral-action time TN
TD Constant TD TD=Derivative-action time TV/Scan time TA
W Setpoint
STEU Control word
YH, dYH Output value: YH Control Word Bit 3=0
dYH Control Word Bit 3=1
Z Disturbance variable
XW System error
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a
a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a
a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a
a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a
a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
X Actual value
XZ Substitute value for system error
Y, dY Manipulated variable, manipulated increments
BGOG Upper limit of the manipulated variable
BGUG Lower limit of the manipulated variable
YA, dYA Output value : YA Control Word Bit 3=1
dYA Control Word Bit 3=0
9-4 EWA 4NEB 812 6210-02