Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 605

Tracking
For tracking, there are two functions as shown below.
Item
Bumpless function
Output limiter processing function
When tracking is required, connect CASOUT_T of the primary loop with CASIN_T of the secondary loop. In
addition, settings for the following operation constants of the secondary loop are necessary.
• PID_TRK
• PID_SVPTN_BO
• PID_SVPTN_B1
For details, refer to the following.
Page 604 Cascade connection when tracking is required
Ex.
Tracking of cascade loop
In the control loops constituting the cascade loop, SV of the secondary loop is transferred to MV of the primary loop to prevent
a sharp change of SV at the control mode switching in the secondary loop.
SV
TIC
MV
PV1
Primary control loop
PV2
Secondary control loop
(1) If the control mode of the secondary control loop is other than CASCADE and tracking processing function is valid, SV of the secondary loop is transferred
to MV of the primary loop, and tracking processing is performed. When the operation mode of the secondary loop is switched from AUTO to CASCADE, MV
sharp change can be prevented since SV of the secondary loop is the same as MV of the primary loop.
The mode switching of the secondary loop is: CASCADE  AUTO  MANUAL. The MANUAL mode can be switched to the CASCADE mode through
AUTO mode. The CASCADE mode can be switched to the MANUAL mode through AUTO mode.
Secondary loop
SV
CASCADE
(2) Not tracked: SV of the secondary loop is sharply changed.
(3) Tracked: SV of the secondary loop is not sharply changed.
Description
At AUTO  MANUAL mode switching, this function prevents the step change caused by the sharp change of the
manipulated variable (MV) output and allows MV bumpless switching.
This function sets the upper/lower limit for the manipulated variable (MV) that is output by PID operation in the AUTO
mode.
The output limiter processing function is valid only in the AUTO mode. It cannot be executed in the MANUAL mode.
Even if the primary loop is in the AUTO mode, the output limiter processing function is not executed while the primary
loop is being tracked by the secondary loop since the tracking data is stored as the manipulated value.
(1)
SV
FIC MV
AUTO
(2)
(3)
CASCADE
Appendix 3 Related Functions of Process
A
APPX
603