Product data

38
Modicon
™
Quantum
™
Ethernet I/O
automation platform
Unity
™
Pro software
Small / Medium / Large / Extra Large / XLS
Programmable process control
Introduction,
Functions
Process control in machines
Unity
™
Pro contains CONT_CTL, a library of 36 function blocks used to create
control loops for machine control.
Requirements for closed loop control functions in machines are adequately met by
Modicon
™
M340
™
, Premium
™
and Quantum
™
platforms due to the wealth of functions
in the library and the exibility of linking function blocks together through
programming. This solution helps to eliminate the need for external controllers and
simplies the overall control architecture of the machine, as well as its design,
installation, commissioning and operation.
The EFs or EFBs can be used in Unity Pro languages (LD, ST, IL and FBD). FBD is
particularly suitable for accessing control processing operations in Unity Pro through
its wizard for entering and viewing parameters and function block variables.
CONT_CTL library functions
The library consists of ve function families:
Input data conditioning b
Controllers b
Mathematical functions b
Process value processing b
Output value processing b
Input data conditioning
DTIME
Pure delay time
INTEGRATOR
Integrator with limiting
LAG_FILTER
First order time lag
LDLG
Lead/lag function with smoothing
LEAD
Lead function with smoothing
MFLOW
Mass ow calculation based on the measurement of differential
pressure or ow speed with pressure and temperature
compensation
QDTIME
Dead time term
SCALING
Scaling
TOTALIZER
Integrator (typically of ow) until a limit (typically a volume) is
reached, with automatic reset
VEL_LIM
Velocity limiter, with manipulated variable limiting
Controllers
PI_B Basic PI controller: PI algorithm with a mixed structure
(series/parallel)
PIDFF Complete PID controller: PID algorithm with a parallel or mixed
structure (series/parallel)
AUTOTUNE Automatic tuner setting for the PIDFF (complete PID) controller or
the PI_B (basic PI) controller
Identication using Ziegler Nichols type method
b
Modelling based on rst order process
b
Building of control parameters with criterion for prioritizing
b
either the reaction time to disturbance (dynamic) or the stability
of the process
IMC Model-based controller. The model is a rst order model with
delay. This controller is useful:
When there are serious delays compared with the main time
b
constant of the process; this scenario cannot be satisfactorily
resolved by standard PID process control
For regulating a non-linear process
b
IMC can handle any stable and aperiodic process of any order
SAMPLETM Control of controller startup and sampling
STEP2 Simple two-position controller
STEP3 Three-position controller for temperature regulation
Mathematical functions
COMP_DB Comparison of two values, with dead zone and hysteresis
K_SQRT Square root, with weighting and threshold, useful for linearization
of ow measurements
MULDIV_W Weighted multiplication/division of 3 numerical values
SUM_W Weighted summing of 3 numerical values
CONT_CTL, programmable process control integrated in
Unity Pro
AUTOTUNE
PV
SP
RCPY
START
PREV
PARA
TR_I
TR_S
PV_O
SP_O
PARA_C
TRI
TRS
INFO
STATUS
TT18_PV
TT18_SP
TC18_OUT
TC18_START
TC18_PREV
TC_PARA
TC18_PARA
TC18_OUT
1
TC2_OUT
TC2_OUT
TC18_OUT
PV
SP
PARA
TR_I
TR_S
PIDFF
FF
RCPY
MAN_AUTO
OUT OUT
OUTD
MA_O
INFO
STATUT
TC2_OUT
MS
TC18_OUT
IN
PARA
TR_I
TR_S
FORC
MA_FORC
MAN_AUTO
OUT OUT
OUTD
MA_O
STATUT
Example: PID controller with MS manual control