Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 604

■Cascade direct
For 2PIDH tags, the CASCADE DIRECT mode can be selected as the control mode. In the cascade direct control, the output
value of the primary loop is directly output as that of the secondary loop in the cascade connection.
In case of the input sensor failure in the secondary loop, the output result of the primary loop is substituted for and directly
output as the output value of the secondary loop since the PID operation result of the secondary loop will be improper.
The CASCADE DIRECT mode can be set with the tag of the secondary loop.
Flow fluctuation
Fuel tank
(1) MV of the primary loop is used as MV of the secondary loop.
APPX
602
Appendix 3 Related Functions of Process
SV
Primary control loop
TIC
(temperature control)
001
PV MV
PV
Sensor failure
Flow sensor
SV
(1)
FIC
Secondary control loop
MV
(flow control)
002
Valve
Thermocouple
Burner
Furnace