Set point
value (SP)
Temperature
Auto-tuning offset value
Auto-tuning in
forward operation
(SP’)
Time
Auto-tuning PID control
Calculate Kp, Ti and Td
■
Precautions for programming
● The operand [S4] through [S4+29] areas are initialized when the execution condition is
switched on. If values other than default are to be used, set them using the MV instruction,
etc.
● PID operation instructions are always internally calculating operation intervals, PWM output
timings, etc. Ensure that the operation instructions are carried out only once in every scan.
Additionally, do not attempt to execute it during a subroutine or interrupt program. At the
same time, it is not possible to describe multiple EZPID instructions specifying the same
operand.
● Do not switch off the execution conditions during PID operation. Otherwise, PID processing
will be disabled.
● If you do not want to synchronize the PWM output cycle for controlling multiple objects, you
can delay the startup timing, for example by adjusting the startup condition rise time.
● The system does not operate correctly if two or more PID instructions specifying the same
table are described in the program. Even if execution conditions are not met, PID instructions
operate internally using the specified table. In such cases, set the tables to separate
addresses.
● Ensure that the work area for PID operation is not rewritten by other instructions.
● Error is not detected even if the parameter table exceeds the area. Ensure to specify a
number at least 30 words before the final number of each device (such as the data register)
when specifying the [S4] area. Also ensure that the area is not exceeded by index
modification. Error is not detected even if the area is exceeded.
● Execution conditions vary immediately after the EZPID instruction, just like PWM output.
Therefore, the system does not operate correctly if the subsequent instructions are
described.
10.12 EZPID (PID Operation: PWM Output Available)
10-52 WUME-FP7CPUPGR-12
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