284
Death Region [S3+7]
If the measured value changed slightly for a long time, and PID control is still in working
mode, then it belongs to meaningless control. Via setting the control death region, we can
overcome this situation. See graph below:
Suppose: we see the death region value to be 10. Then in the above graph, the difference is
only 2 comparing the current value with the last value. It will not do PID control; the
difference is 13 (more than death region 10) comparing the current value with the next value,
this difference value is larger than control death region value. it will do the PID control with
135.
7-4
.
Auto Tune Mode
If users do not know how to set the PID parameters, they can choose auto tune mode which
can find the best control parameters (sampling time, proportion gain
Kp
, integral time
Ti
,
differential time
TD
) automatically.
Auto tune mode is suitable for these controlled objects: temperature, pressure; not suitable for
liquid level and flow.
Auto-tuning is the process of extracting PID parameters. Sometimes auto-tuning can not find
the best parameters at one time. It needs auto-tuning for many times. It is normal that there is
a vibration in the process. After the optimum parameters are found at the end of auto-tuning,
please switch to the manual PID mode. If the control object is unstable in the process of
manual PID, it can not be controlled at a constant target value, which may be caused by the
unsatisfactory adjustment of parameters. It is necessary to re-adjust the parameters of PID to
achieve stable control.
For step response method: Users can set the sampling cycle to be 0 at the beginning of the
auto tune process then modify the value manually in terms of practical needs after the auto
tune process is completed.
Содержание XD Series
Страница 1: ...XD XL series PLC User manual Instruction WUXI XINJE ELECTRIC CO LTD Data No PD05 20201022 3 5 ...
Страница 210: ...209 ...
Страница 314: ...313 B Double click the middle part to modify ...