Description of the regulation functions
Programming the SERVO function
Introduction The SERVO function is a standard PL7 function. As such, it is available from the functions library.
From the language editors there, it is possible to use the help of a SERVO function’s input to facilitate its programming.
Note: The SERVO function’s input can be done in any periodic task (MAST or
FAST). The function does not have to be conditioned.
Illustration The illustration below gives you a general idea of the Functions screen in the library supporting the implementation of the SERVO function.
EF
Information Functions: Parameters
Family
Single precision reals
Process Control
Integer tables
Bit tables
Integer tables
Integer tables
Call format
Lib.V App.V.
2.22
2.01
2.00
2.00
2.10
2.00
-
-
-
-
-
-
PID
Name
PID_MMI
PWM
SERVO
Mixed PID regulator
Management of operator dialogue dedicated to CCX17 from PID
Modulated in the pulse width of a numerical size
PID output stage for open/close valve order
Parameters of the PROCEDURE:
Name Type
INP WORD
Kind Comment
Position setpoint, format [0;10000] (to conn>>
POT
UP
DOWN
WORD
EBOOL
EBOOL
IN
IN
OUT
OUT
Position copy, format [0;10000] [-10000>>
Alternating output, UP operating direction
Alternating output, DOWN operating direction
OUTP
-10000
%Q2.1
Comment
%MW100:43
Entry field
Call display
SERVO ( OUTP,-10000,%Q2.1,%MW100:43,%MW180:10 )
Syntax The SERVO function’s call syntax is:
SERVO(INP,POT,UP,DOWN,PID,PARA)
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TLX DS 37 PL7 xxE
Description of the regulation functions
Parameters of the SERVO function
Parameter
INP
POT
UP
DOWN
PID
PARA
The table below presents the different parameters of the SERVO function.
Type
%MWi
%MWi or direct
%Qxy.i or %Mi bit type %Q or
%M
%MWi:43
Kind
IN = Input
OUT = Output
IN
Description
IN
OUT
OUT
IN / OUT
Position setpoint ([0 – 10000] format) that has to be connected to the PID output.
Position copy, ([0 - 10000] format)
0 : closed valve; 10000: open valve.
If the copy does not exist. POT must be initialized at –10000.
This particular value indicates "no copy".
Output signal for the motor’s UP operating direction.
Output signal for the motor’s DOWN operating direction.
%MWi:10 IN / OUT
The PARA parameter table of the upstream PID. Used if there are no copy words for the synchronization with the upstream
PID. See
Parameters of the PID function, p. 362 .
(See the table below for the breakdown of the PARA table).
The table below presents the different parameters of the PARA table:
Parameter
T_MOTOR
T_MINI
HYST
Position
%MWi
%MW(i+1)
%MW(i+2)
Function
Valve opening time shown in 10
-2
s.
Used if the copy does not exist (POT = -10000).
Minimal pulse time shown in 10
-2
s.
Used if the copy does not exist (POT = -10000).
Value of the hysteresis on the [0 – 10000] format.
Used if the copy does not exist (POT: [0 - 10000]).
Note: l The other parameters that are used by the function’s internal management must never be modified by the application.
l All the parameters are obligatory, regardless of the operating mode.
TLX DS 37 PL7 xxE
375
Description of the regulation functions
Examples The examples offered below are done in Ladder language.
Case with a position copy.
OPERATE
PID(‘PID1’,’m/s’,PV,OUTP,MAN_AUTO>> with PID(‘PID1’,’m/s’,PV,OUTP,MAN_AUTO,%MW100:43)
OPERATE
PID(‘TEMP’,’DEGRES’,%MW10,%MW1>> with SERVO(OUTP,%IW3.1,%Q2.1,%Q2.2,%MW100:43,%MW180:10)
Case without a position copy.
OPERATE
PID(‘PID1’,’m/s’,PV,OUTP,MAN_AUTO>> with PID(‘PID1’,’m/s’,PV,OUTP,MAN_AUTO,%MW100:43)
OPERATE
PID(‘TEMP’,’DEGRES’,%MW10,%MW1>> with SERVO(OUTP,-10000,%Q2.1,%Q2.2,%MW100:43,%MW180:10)
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TLX DS 37 PL7 xxE
