User guide

Chapter 26
PID Instruction
26–20
Notes on Operation
A 3-digit BCD thumbwheel is wired to an input
module at I1:1.0 (range 0–100).
A pushbutton wired to I1:2.0/0 accepts the
thumbwheel value.
A selector switch for auto/manual mode is wired
to I1:2.0/1 (auto) and I1:2.0/2 (manual).
N7:0 stores the value entered on the
thumbwheel switch.
N7:2 stores an intermediate calculation.
N7:8 is the PID control variable address.
N7:10 is the control block address of the PID
instruction.
N7:26 Percent output is updated automatically
by the PID instruction.
] [
N7:10
1
[OSR]
B3
0
( )
B3
3
MUL
MULTIPLY
Source A N7:0
Source B 16384
Dest N7:2
LIM
LIMIT TEST
Low Lim 0
Test N7:0
High Lim 100
FRD
FROM BCD
Source I1:1.0
Dest N7:0
DDV
DOUBLE DIVIDE
Source 100
Dest N7:8
] [
I:2.0
0
(U)
S:5
0
] [
I:2.0
1
Accept CV
Error – Out of Range
Auto
] [
I:2.0
2
Manual
(L)
N7:10
1
(U)
N7:10
1
A/M Bit
A/M Bit
A/M Bit
LIM
LIMIT TEST
Low Lim 101
Test N7:0
High Lim –1
Example – To Manually Control the CV Output