Selftuning - gefran GFX4 Configuration And Programming Manual

SELFTUNING

This function is valid for single-action (either heat or cool) systems and for double-action (heat/cool) systems.
Selftuning is activated to calculate the best control parameters when starting the process. The variable (example:
temperature) must be the one assumed at zero power (room temperature).
The controller supplies the maximum power set until reaching an intermediate point between starting value and the setpoint,
then resets power. The PID parameters are calculated by evaluating superelongation and the time needed to reach the peak
(N.B.: This action is not considered in ON/OFF control).
When the function is completed, it disengages automatically, and the control proceeds to reach the setpoint.
Selftuning
Process
variable
S.P.
Peak
S.P. - t.a.
2
t.a.
The procedure runs automatically until termination. At termination, the new PID parameters are saved: proportional band,
integral and derivative times calculated for the current action (heat or cool). In case of double action (heat + cool), the parameters
for the opposite action are calculated by maintaining the initial ratio between the parameters (example: Cpb = Hpb * K; where K =
Cpb / Hpb when selftuning is started). At termination, the Stu code is automatically cancelled.
Note: The procedure does not start if temperature exceeds the setpoint for heat control, or is below the setpoint for cool control.
In this case, the Stu code is not cancelled. It is advisable to enable the LEDs to signal selftuning state. By setting parameter Ld.St
= 4 on the Hrd menu, the appropriate LED will light up or flash when selftuning is active.
31
s. t v
140
diG.
618
diG. 2
3
SELFTUNING
bit
305
50
T
Time
Enable selftuning,
R/W
autotuning, softstart
R/W Function digital input
R/W Digital input 2 function
OFF = Selftuning in Stop
R/W
ON = Selftuning in Start
R/W Instrument state
How to activate selftuning:
A. Activation at switch-on
1. Set the setpoint to the desired value.
2. Enable selftuning by setting parameter Stu to 2
3. Switch off the instrument.
4. Make sure that temperature is near room temperature.
5. Switch on the instrument.
B. Activation via serial command
1. Make sure that temperature is near room temperature.
2. Set the setpoint to the desired value.
3. Run the Start Selftuning command.
Selftuning, autotuning, softstart table
S.tu Autotuning
continuous
0 NO
1 YES
2 NO
3 YES
4 NO
5 YES
6 -
7 -
8* WAIT
9 GO
10* WAIT
11 GO
12* WAIT
13 GO
(*) +16 with automatic switching in GO if PV-SP > 0.5% f.s.
+32 with automatic switching in GO if PV-SP > 1% f.s.
+64 with automatic switching in GO if PV-SP > 2% f.s.
+128 with automatic switching in GO if PV-SP > 4% f.s.
See: Table of digital input functions
See: Table of instrument settings
880397M_MSW_GFX4-GFXTERMO4_08-2018_ENG
see: CONTROLS - PID parameters
Selftuning Softstart
NO NO
NO NO
YES NO
YES NO
NO YES
NO YES
- -
- -
NO NO
NO NO
YES NO
YES NO
NO YES
NO YES
0
0
0
0