Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 208

Process control function blocks
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■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
■Inverse engineering value conversion
This function block converts the setting value (SV) of an engineering value into a setting value (SV) in percentage (%).
100
SV(%)=
×(SV-RL)
RH-RL
RH: Engineering value high limit, RL: Engineering value low limit, SV: Setting value
■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 block sets whether to detect alarms (ALM) or not in the deviation check.
Item
Disable alarm detection by setting tag data
Disable alarm detection by loop stop processing
■Auto tuning (AT1)
This function block detects dynamic characteristics and automatically calculates a proportional gain (Kp), integral time (Ti),
and derivative time (Td) for PID operations. ( Page 594 Auto tuning)
• 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.
• Auto tuning can be performed only in the MANUAL mode.
■Loop stop processing
When the stop alarm (SPA) of the alarm (ALM) is TRUE, this function block performs the following processing.
• MV is cleared to 0.
• The control mode is automatically switched to MANUAL.
• When DVLA of the alarm (ALM) has occurred, the DVLA is reset.
• No alarm is detected in the deviation check.
10 LOOP CONTROL OPERATION
206
10.5 2-degree-of-freedom PID Control (Enable Tracking for primary loop) (M+P_2PID_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) are TRUE, no DVLA of
the alarm (ALM) will be detected.
• ERRI
• DVLI
Page 206 Loop stop processing
Result
The input variable CASIN_T is tracked.
The input variable CASIN_T is not tracked.

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