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
−
=
−
−
−
PI
PI
PV
PV
PV
T
T
D
D
EV
T
T
EV
EV
K
PI
PV
SV
EV
n
n
n
S
D
n
n
n
I
s
n
n
P
n
n
2
1
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)
PDF compression, OCR, web optimization using a watermarked evaluation copy of CVISION PDFCompressor
