IDEC MicroSmart Pentra - Manual (Page 39)

PID M ODULE M AIN F UNCTIONS
4-16 FC5A MicroSmart PID Module User’s Manual FC9Y-B1283
How to perform auto-tuning (AT) in cascade control
Auto-tuning (AT) can be performed for the cascade control with the following procedure.
Auto-tuning (AT) for the slave (CH0)
1. Turn off the CH0 and CH1 control enable bits of the operation parameter to disable the CH0 and CH1
controls.
2. Copy the set point (SP) of the master (CH1) to the set point (SP) of the slave (CH0), the external SP
input linear conversion maximum value, and the external SP input linear conversion minimum value
in order to fix the set point (SP) of the slave (CH0).
3. Turn on the CH0 and CH1 control enable bits of the operation parameter to enable the CH0 and CH1
controls. Turn on the CH0 auto-tuning (AT)/auto-reset bit of the operation parameter to start the
auto-tuning (AT) for the slave (CH0).
When auto-tuning (AT) is completed, P, I, D and ARW values of the slave (CH0) will be automatically
configured.
Auto-tuning (AT) for the master (CH1)
4. Turn off the CH1 control enable bit of the operation parameter to disable the CH1 control.
5. Store the original values in the external SP input linear conversion maximum and minimum values.
6. Turn on the CH1 control enable bit and CH1 auto-tuning (AT)/auto-reset bit of the operation parame-
ter to enable the CH1 control and start the auto-tuning (AT) for the master (CH1).
When auto-tuning (AT) is completed, P, I, D and ARW values of the master (CH1) will be automati-
cally configured
Notes:
• When using the cascade control, store the same set point of the master (CH1) to the set point (SP) of the slave
(CH0).
• The output manipulated variable (MV) (0 to 100%) of the master (CH1) corresponds to the set point (SP) of the
slave (CH0). The range of the set point is the external SP input linear conversion minimum value to the external
SP input linear conversion maximum value.
• Depending on each control target, optimum values of P, I, D and ARW may not be calculated with the auto-tuning
(AT). In such case, configure those parameters manually based on the P, I, D and ARW values calculated with the
auto-tuning (AT).
Program Example of Auto-tuning (AT) for Cascade Control
A sample ladder program to execute the auto-tuning (AT) for the master (CH1) and slave (CH0) in the
cascade control is described in the following page.