Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 220

■Engineering value conversion
This function block converts the setting value (%) from the primary loop in the CAS or CSV mode into an engineering value.
RH-RL
× Setting value (%) from the primary loop + RL
SV=
100
RH: Engineering value high limit, RL: Engineering value low limit, SV: Setting value (target)
■Inverse engineering value conversion
This function block converts SVC of an engineering value into SVC in percentage (%).
100
SVC(%)= ×(SVC-RL)
RH-RL
RH: Engineering value high limit, RL: Engineering value low limit, SVC: Setting value (current)
■Tracking processing
The following table shows whether tracking processing to the input variable CASIN_T is performed or not.
Condition
Tracking Flag (TRK)
1
0
■Disable alarm detection
This function sets whether to detect alarms (ALM) or not in the deviation check and SV variation rate & high/low limiter
processing.
Item
Disable alarm detection by setting tag data
Disable alarm detection by control mode selection
Disable alarm detection by loop stop processing
■Auto tuning (AT1, AT2)
This function block detects dynamic characteristics and automatically calculates a proportional gain (Kp), integral time (Ti),
and derivative time (Td) for PID operations.
Select the step response method or the limit cycle method for auto tuning.
• AT1 (Step response method)
Auto tuning is for setting initial values of the proportional gain (Kp), integral time (Ti), and derivative time (Td) for PID
operations. The ZN method: Ziegler-Nichols' step response method is used for calculating the values. ( Page 595 Step
response method)
This method can be used in the MAN or CMV mode.
• AT2 (Limit cycle method)
In this method, a proportional gain (Kp), an integral time (Ti), and a derivative time (Td) for PID operations are calculated from
the variation amplitude and variation cycle of a process variable obtained by repeatedly outputting the high and low limit
values of a manipulated value. ( Page 598 Limit cycle method)
This method can be used in the MAN, AUT, CAS, CMV, or CSV mode.
10 LOOP CONTROL OPERATION
218
10.7 2-degree-of-freedom Advanced PID Control (Enable Tracking for primary loop) (M+P_2PIDH_T_)
Setting Value (SV) Used (SVPTN_B0)
FALSE
TRUE
FALSE or TRUE
Disable alarm detection processing
If the following bits in the disable alarm detection (INH) and the disable alarm
detection 2 (INH2) are TRUE, DVLA of the alarm (ALM), or DSVLA, SVHA, or
SVLA of the alarm 2 (ALM2) will not be detected.
• ERRI
• DVLI
• DSVLI
• SVHI
• SVLI
No alarm will be detected when the control mode is CASDR.
Page 220 Loop stop processing
Result
The input variable CASIN_T is tracked.
The input variable CASIN_T is not tracked.