F356_Parameters_NonHold_DUT

This DUT can be used with the following instruction(s): F356_PID_PWM.

This DUT specifies the manipulated value (MV) and the control parameters (4 words).

MV (INT)

Stores the manipulated value (output value)

Default value 0

Setting range -10000–10000

LowerLimit (INT)

Sets the lower limit of the manipulated value MV

Default value 0

Setting range min. -10000

UpperLimit (INT)

Sets the upper limit of the manipulated value MV

Default value 10000

Setting range max. 10000

PV_Band_WithFullOutput (INT)

No PID control is performed and the output is at 100% until the defined level (0–80%) of the set point value has been reached.

Default value 0

Setting range 0–80%

Ts (INT)

Sets the sampling time for updating the measured input values.

Unit = 0.01s

Also sets the PWM output period.

Default value 100 (1s)

Setting range 1–3000 (0.01–30s)

ControlMode (WORD)

• 0: Inverse PI-D control, e.g. heating
• 1: Forward PI-D control, e.g. cooling
• 2: Inverse I-PD control, e.g. heating
• 3: Forward I-PD control, e.g. cooling

Default value 0

Setting range 0–3

AT_Bias (INT)

Sets a bias value for performing auto-tuning

Default value 0

Setting range min. 0

AT_Correction_Kp (INT)

Sets the correction value of the auto-tuning result for Kp

Default value 125%

Setting range 50–500%

AT_Correction_Ti (INT)

Sets the correction value of the auto-tuning result for Ti

Default value 200%

Setting range 50–500%

AT_Correction_Td (INT)

Sets the correction value of the auto-tuning result for Td

Default value 100%

Setting range 50–500%

AT_Progress (INT)

Stores the auto-tuning progress

Default value 0

Setting range 0–5

WorkingArea (ARRAY..OF..INT)

Working area of up to 30 words for PID processing and auto-tuning

Default value 0

Detailed information on the setting method:

• PV_Band_WithFullOutput

  Define the percentage of the set point value at which PID control should start. Below this level, output is at 100%.

  For example, if PV_Band_WithFullOutput is set to 80% and the measured value (process value PV) is only at 50% of the set value, the output will be at 100%. It will remain at 100% until the measured value reaches 80% of the set value, at which point PID control will start.

  The amount of the percentage determines how quickly the set value will be reached.

• Fine adjustment of auto-tuning

  When auto-tuning has completed, the parameters for Kp, Ti and Td are stored in the elements of F356_Parameters_Hold_DUT. For fine adjustment, you can now correct the result of auto-tuning with the parameters AT_Correction_Kp, AT_Correction_Ti and AT_Correction_Td.

  Example

  Set AT_Correction_Kp to 200 (i.e. 200%): perform auto-tuning to correct Kp to double its value.

  Set AT_Correction_Ti to 125 (i.e. 125%): perform auto-tuning to correct Ti to 1.25 times its value.

  Set AT_Correction_Td to 75 (i.e. 75%): perform auto-tuning to correct Td to 0.75 times its value.

• Auto-tuning bias value

  • If a bias value has been set, auto-tuning will be performed with a temporary set point value SP’.

  • In reverse operation, SP' is the difference of the set point value SP and the auto-tuning bias value. The auto-tuning bias value can be used to control excessive temperature rise during auto-tuning.

  • In forward operation, SP' is the sum of the set point value SP and the auto-tuning bias value.

    KP, TI and TD calculation

    

    1.  (1) Temperature
    2.  (2) Set value
    3.  (3) Auto-tuning bias value
    4.  (4) Auto-tuning in reverse operation
    5.  (5) During auto-tuning
    6.  (6) PID control
    7.  (7) Time
    8.  (8) Auto-tuning in forward operation
    NOTE

    Auto-tuning is peformed with SP’ even if the measured process value is close to the set point value SP when auto-tuning starts.