Tecnologic TLK 94 Operating Instructions Manual Download Page 7

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and the result of the PID control algorithm with two degrees of
liberty for the instrument.

The control system used does not foresee a retroaction for finding
the current position of the actuator.

If the actuator is not fitted with safety stop contacts that interrupt
the actuator at the end of its run it is necessary to equip the

installation with these contacts (SQo, SQc) as shown in the
diagram

S u p p l y

C L O S E

O P E N

S Q o

1 . r E G

2 . r E G

S Q c

T L K 9 4

The PID control algorithm for motorised actuators with time

positioning foresees the setting of the following parameters:

“Pb”

- Proportional band

“Int”

- Integral time

“rS”

- manual reset (only if “Int =0)

“dEr”

- Derivative time

“FuOC” -

Fuzzy Overshoot Control

“tcor”

- time of actuator run.

This is the time, expressed in seconds that is needed for the

actuator to pass from the “completely open” position to “completely
closed” position.

“SHrI”

- Minimum control value.

It is the value that the control must have reached (in %) before it
has an effect on the output. It is needed to prevent the control from

intervening too frequently.

“PoSI”

- Switch on position.

This is the position that the actuator must reach when the

instrument is switched on. It can have the following values :
nO = the actuator remains where it is,

oPEn = the actuator goes to the “completely open” position,
cLoS = the actuator goes to the “completely closed” position.

If the options "OPEn" or "CloS" are programmed, when it is turned
on the device with activate the output 1.rEG (if "oPEn") or 2.rEG (if

"cLoS") for the time set on parameter "tcor" after which control
begins.

In the event of an error in measurement, the outputs are activated
so that the valve moves to the position fixed by the parameter

“PoSI”.

4.8 - AUTOTUNING

AND SELFTUNING FUNCTIONS

All the parameters referring to the AUTO-TUNING and
SELF-TUNING functions are contained in the group

“

]

rEG”.

The AUTO-TUNING and SELF-TUNING functions permit the

automatic tuning of the PID controller.
The

AUTO-TUNING

function (

FAST

OSCILLATING

type)

permits the calculation of the PID parameters by means of a tuning

cycle and, at the end of this operation, the parameters are stored
into the instrument’s memory and remain constant during control.
The

SELF-TUNING

function (rule based "TUNE-IN") instead allows

control monitoring and the continuous calculation of the parameters
during control.

All functions automatically calculate the following parameters :

"Pb"

- Proportional Band

"tcr1"

- Cycle time of the output 1.rEG

"Int"

- Integral Time

"dEr"

- Derivative Time

“FuOC” -

Fuzzy Overshoot Control

and, for the Double Action PID control, also :

“tcr 2”

- Cycle time of the output 2.rEG

"Prat"

- Ratio P 2.rEG/ P 1.rEG

To activate the AUTO-TUNING function proceed as follows :

1) Program and activate the desired Set Point.
2) Program par. "Cont" =Pid or =3 Pt if the instrument drives a

motorized actuator with time positioning.
3) Program par. "Func" according to the process to be controlled

through output 1.rEG.
4) Program an output as 2.rEG if the instrument controls a plant

with double action or a motorized actuator with time positioning.
5) Set the parameter

"Auto"

as:

= 1

- if FAST autotuning is desired automatically, each time the

instrument is switched on, on the condition that the process value

is lower (with “Func” =HEAt) than [SP- |SP/2|] or higher (with
“Func” =CooL) than [SP+ |SP/2|].

= 2

- if FAST autotuning is desired automatically, the next time the

instrument is switched on, on the condition that the process value
is lower (with “Func” =HEAt) than [SP- |SP/2|] or higher (with

“Func” =CooL) than [SP+ |SP/2|], and once the tuning is finished,
the par. “Auto” is automatically swapped to the OFF state

= 3

- if manual FAST autotuning is desired, by selecting par. “tunE”

in the main menu or by key “U” correctly programming as “USrb” =
tunE. The Autotuning will start at the condition that the process

value is lower (with “Func” =HEAt) than [SP- |SP/5|] or higher (with
“Func” =CooL) than [SP+ |SP/5|].

= 4

- if it’s desired to activate the FAST autotuning automatically at

the end of programmed Soft-Start cycle or each time the Set Point
is changed. The Autotuning will start at the condition that the

process value is lower (with “Func” =HEAt) than [SP- |SP/5|] or
higher (with “Func” =CooL) than [SP+ |SP/5|].

= - 1

- if the OSCILLATING autotuning is to be started automatically

each time the instrument is turned on.

= - 2

- if the OSCILLATING autotuning is to be started

automatically when the instrument is turned on the next time and,

once tuning has been completed, the parameter “Auto"=OFF is set
automatically.

= - 3

- if OSCILLATING autotuning is started up manually, by

selecting par. “tunE” in the main menu or by key “U” correctly
programming as “USrb” = tunE.

= - 4

- if OSCILLATING autotuning is to be started automatically

each time the Set Point is changed.

Note : the Autotuning Fast type is particularly rapid and has no
effect on the control as it calculates the parameters during the Set
Point reaching phase.
In order to correctly perform the Autotuning Fast type it’s necessary
that at the start of the cycle there is a certain difference between
the process and the Set Point and for this reason the instrument
activates the Autotuning Fast type only when :
- For “Auto” = 1 or 2: the process value is lower (with “Func”
=HEAt) than [SP- |SP/2|] or higher (with “Func” =CooL) than [SP+
|SP/2|].
- For “Auto” = 3 or 4 : the process value is lower (with “Func”
=HEAt) than [SP- |SP/5|] or higher (with “Func” =CooL) than [SP+
|SP/5|].
The Autotuning Fast type is not advisable when the Set Point is
next to the initial reading or when the measured variable changes
irregularly during the tuning cycle (for reasons due to the process
the variable goes up or down).
In this cases we advice the Autotuning oscillatory type that
activates some ON-OFF control cycles permitting the oscillation of
the process value around the Se Point value and afterward the
control swap to the PID type with those values calculated by the
Autotuning.