ABB ControlMaster CM10 User Manual page 31

ControlMaster CM10, CM30 and CM50
Universal process controllers,
...Basic / ...Loop 1 Control
Mode
Autotune
Autotune Operation
Autotune is a user-activated feature that enables automatic setting of the controller PID parameters (see page 30) using an
' '
at setpoint type algorithm. Autotune changes the controller output and then monitors the process response to calculate
the optimum PID settings. Autotune uses a relay type function with hysteresis that initiates a controlled oscillation in the
process. New PID parameters are calculated and stored in the controller automatically. Note. To achieve the best results
from Autotune, switch the controller to Manual control mode (see page 5) and adjust the output until the PV is stable (close
to the normal setpoint) before initiating Autotune.
SP
A
B
C
PV
IM/CM/S–EN Rev. R
1 1 1
/ , / and / DIN
8 4 2
Turns the Autotune functionality on or off.
When set to On, an Autotune can be started from the Operator level menus – see page 22.
1
Set the first step value and dynamics required. For best results, select the largest initial
output step size that can be tolerated by the process.
D
2
Autotune is enabled only if the control type is PID.
3
Start Autotune from the Operator menu.
Monitors a noise A and calculates a hysteresis value.
4
User-defined initial step in the output B. When the process exceeds the hysteresis
5
value the output is stepped down.
Adjusts output amplitude automatically C so PV disturbance is kept to minimum
6
required.
When consistent oscillation is established D, the Autotune process stops. Optimum
7
settings are calculated from the process dynamics monitored.
6 Basic Level
29