4
7.Determining PID Constants(Auto-tuning)
When AT is executed, the optimum PID constants for the set point at that time are set automatically. A
method (called the limit cycle method) for forcibly changing the manipulated variable and finding the
characteristics of the control object is employed.
Set parameter HY as 0.5, if the output is relay set the t as 2, then set the AT as 1, in this time the
controller enter into
Auto-tuning
. PV window will
alternately Display “AT” and PV value, now
meter’s control way is on-off mode, after 3 times
vibrating( 3 control period) automatic save P, I, D
parameter, the self-adjusting procession finished.
Operation will be as shown in the following diagram:
Attentions
：
when
Auto-tuning
, the controller should not
change the set value.
When the power off during
Auto-tuning
, it will
restart
Auto-tuning
next time.
When it need artificially exit during
Auto-tuning
, set the Parameter(AT) to 0 so that can exit
，
but the
setting result will not be valid.
8.
Alarm function
Alarm (ALM) function
Alarm status[ON]
Alarm status[OFF]
Process high alarm
Measured value>Alarm set value
Measured value<Alarm set value
