Chapter 6 FBD Block  Diagram Programming    176 
PID (Proportion- Integral- Differential) function block 
There is a maximum of 30 PI (PID) function blocks under FBD mode, and the function is same as Ladder mode. 
 
PID computes formula: 
()
()
∑
Δ=
−−=
⎭
⎬
⎫
⎩
⎨
⎧
++−=Δ
−=
−−
−
PIPI
PVPVPV
T
T
D
DEV
T
T
EVEVKPI
PVSVEV
nnn
S
D
n
nn
I
s
nnP
nn
21
1
2
 
Parameters can be constant or other function current value. The output coil will turn ON when either T
S
 or K
P
 is 0. 
 
Example: 
 
 
FBD display: 
 
Enable Input 
→ 
 
Parameter 
→ 
 
 
Parameter display: 
  Parameter display 1  Parameter display 2   
PID current value 
→ 
 
Destination value 
→  ← 
Proportional gain
Test value 
→  ← 
Integration time 
Sampling time 
→ 
← 
Differential time 
  ※ Display PID current value when running mode; 
※ Test value (PV) display code A02 when stopping mode, and display current value (as example PV= 00770) 
when running mode. 
※ Press “SEL+←→” button can convert between display1 and display2. 
※ More information about PID function to see Chapter 4: Relay Ladder Logic Programming—PID. 
PI: PID current value (-32768~32767) 
SV: Destination value (-32768~32767)
PV: Test value (-32768~32767) 
T
S
: Sampling time (1~32767 * 0.01s) 
K
P
: Proportional gain (1~32767 %) 
T
I
: Integration time (1~32767 * 0.1s) 
T
D
: Differential time (1~32767 * 0.01s)
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