Pixsys DRR244 - Tuning Once; Synchronized Tuning; Digital Input Functions

14 - DRR244 - User manual
To avoid an overshoot, the treshold where the controller calculates new PID parameters is determined
by this operation:
Tune threshold = Setpoint -
“Set Deviation Tune” (par. 74 s.d.t.1 or par. 99 s.d.t.2)
Ex.: if the sepoint is 100.0 °C and the Par.32
s.d.t.1 is 20.0 °C the threshold to calculate PID parameters
is (100.0 - 20.0) = 80.0 °C.
For a greater precision on PID parameters calculation it is suggested to start the manual tuning
procedure when the process deviates from the setpoint.
7.4 Tuning once
Set once on parameter 73 tun.1, or on parameter 98 tun.2.
Autotuning procedure is executed only once at next DRR244 restart. If the procedure doesn’t work,
will be executed at next restart.
7. 5 Synchronized tuning
Set sYNch . on parameter 73 t u n .1 or on parameter 98 tu n.2.
This procedure has been conceived to calculate correct PID values on multi-zone systems, where each
temperature is influenced by the adjacent zones.
Writing on word modbus 1216 (for regulation loop 1) or 1217 (for regulation loop 2) the controller
works as follows:
Word value Action
0 Tune off
1 Command output OFF
2 Command output ON
3 Tune active
4 Tune completed: command output OFF (read only)
5 Tune not available: softstart function enabled (only reading)
Here below the functioning for regulation loop 1: the master switches-off or turns-on all zones (value
1 or 2 on word 1216) for a time long enough to create inertia on the system.
At this point the autotuning is launched (value 3 on word 1216). The controller executes the procedure
for the calculation of the new PID values. When the procedure ends, the controller switches off the
command output and selects the value 4 on word 1216. The master, who will always read the word
1216, will control the various zones and when all will have finished, will bring to 0 the value of word
1216: the various devices will regulate the temperature independently, with the new calculated values
N.B. The master must read the word 1216 at least every 10 seconds or the controller will automatically
exit the autotuning procedure.
7.6 Digital input functions
The DRR244 functions related to digital inputs, can be enabled by parameters 231 d .i .1 . F. e 239 d.i.2.F..
•
2 t.S w .: Two threshold setpoint modification: with digital input active the DRR244 regulates on SET2,
otherwise reulates on SET1;
•
2 t.S w.i. : Modification of 2 setpoints by digital input with impulse command;
•
3 t.S w.i. : Modification of 3 setpoints by digital input with impulse command,
•
4 t.S w.i. : Modification of 4 setpoints by digital input with impulse command,
•
st./S t. : Start / Stop of the controller by digital input with impulse command,
•
ru n. : The regulation is enabled only with digital input active,
•
HoLd : With digital input active the conversion is locked (visualization maintenance function);
•
tune : Enables/disables the Tuning if par. 73 t u n .1 is selected as manu.;
•
a u . m a .i. : If par. 48 a.ma.1. is selected as enab. or en.sto. , with impulse command on digital input, the
DRR244 switches the related regulation loop, from automatic to manual and vice versa.
•
a u.m a.c. : If par. 48 a.ma.1. is selected as enab. or en.sto. the DRR244 switches to manual the related
regulation loop, with digital input active, otherwise the regulation is automatic.
•
A ct.ty. : DRR244 execute a cooling type regulation with digital input active, otherwise the regulation
is of heating type;