Eaton ELC-PB, Programming Manual

Page: 423 / 728

E L C P r o g r a m m i n g M a n u a l
F o r m o r e i nf o r m a t i o n v i sit :
w w w. e a t o n . c o m
MN05003003E
3-254
API Mnemonic Operands Function
88 D PID
S
1
, S
2
, S
3
, D
PID Calculation
Bit Devices Word devices Program Steps
Type
OP
X Y M S K H KnX KnY KnM KnS T C D E F
S
1
*
S
2
*
S
3
*
D *
PID : 9 steps
DPID: 17 steps
ELC ELCB ELCM
PB PC/PA/PH PV PB PH/PA
32 16 P 32 16 P 32 16 P 32 16 P 32 16 P
Operands:
S
1
: Target value (SV)
S
2
: Present value (PV)
S
3
: Parameters (for 16-bit instruction, uses 20
continuous addresses, for 32-bit instruction, uses 21 continuous addresses)
D
: Output value
(MV)
Description:
1. This instruction is specifically for PID control. PID operation will be executed only when the
sampling time is reached. PID refers to “proportion, integration and derivative”. PID control is
widely applied to mechanical, pneumatic and electronic equipment.
2. After all the parameters are set up, the PID instruction can be executed and the results will be
stored in
D
.
D
must be an unlatched data register. (If users want to designate a latched data
register area, clear the latched registers to 0 at the beginning of the user program.
Program Example:
1. Pre-write the PID parameters into all the registers before executing the PID instruction.
2. This instruction will be executed when X0=ON and the result will be stored in D150. The
instruction will not be executed when X0=OFF and the data will be unchanged.
D150
X0
D100 D1 D0 PID
3. The timing chart for the PID instruction (ELC-PB/PC/PA/PH/PV, ELCB-PB max. operation time
is 474us, ELCM-PH/PA max. operation time is 80us)
A + B B B B B
A+B A+B #1
#2
Scan cycle Scan cycle
Sampling time (Ts) Sampling time (Ts)
Note1: The time for equation calculation during PID operation (ELC-PB/PC/PA/PH/ PV,
ELCB-PB about 430us) (ELCM-PH/PA approx. 72us)