■
Precautions when executing auto-tuning
● Auto-tuning may not be executable depending on the process. In that case, the system
returns to the original parameter operation.
● After auto-tuning is completed, the respective optimal values are stored for proportional gain
[Kp], integral time [Ti], and derivative time [Td]. Before execution, it is necessary to specify
appropriate values (e.g. lower limits) within the respective setting ranges.
● After auto-tuning is complete, store optimal values for proportional gain [Kp], integral time
[Ti], and derivative time [Td]. Be careful that the stored values are not rewritten.
● During auto-tuning, the output values for Kp, Ti and Td are calculated by measuring changes
to process values (PVs) when manipulated values (MVs) are set to the upper limits, as well
as changes to process values (PVs) when manipulated values (MVs) are set to the lower
limits, so that process values (PVs) will be increased or decreased in accordance with the
respective set point values (SPs).
● Changes to manipulated values (MVs) of auto-tuning are completed in three sessions (upper
limit output - lower limit output - upper limit output) in the fewest times possible. If the auto-
tuning progress does not change from 0 after multiple sessions, shorten the control interval
Ts and retry auto-tuning.
■
Operation actions
● [S4] through [S4+29] are initialized when the execution condition is switched on.
● If the parameters for proportional gain [Kp], integral time [Ti], and derivative time [Td] are all
0 at the start of PID operation, they are initialized to [Kp]=1, [Ti]=0 and [Td]=0 respectively,
and operation is continued.
● When the auto-tuning request signal is switched on, bit 1 of [S1] (auto-tuning completion
flag) and [S4+10] (auto-tuning completion code) are cleared.
● Set point values for auto-tuning are operated with the value of the set point value (SP) minus
the bias value as the target value.
● After auto-tuning is correctly completed, values are stored for the calculated Kp, Ti and Td
multiplied by the correction coefficients specified by [S4+7] through [S4+9].
10.12 EZPID (PID Operation: PWM Output Available)
WUME-FP7CPUPGR-12 10-53
To Next Page
Loading...
Need help?
General
