Interrupt Execution (Fixed Scan); When A Safety Program Is Used - Mitsubishi Electric MELSEC iQ-R Series Programming Manual

■Setting the control cycle (CT)
Set the control cycle in the "FB Property" of the engineering tool.
Item Name
CT Control cycle
The following table lists the available tag types and tag access FBs performing operations every control cycle.
Tag type
PID
2PID
2PIDH
PIDP
IPD
BPI
R
ONF2
ONF3
SWM
SEL

Interrupt execution (fixed scan)

The interrupt execution interrupts the timer execution program and executes a program.
Set the program file as a fixed scan execution type program. The program file is executed at the fixed scan interval which has
been set. ( MELSEC iQ-R CPU Module User's Manual (Application))
The fixed scan interval is recommended to set 10ms or more.

When a safety program is used

The safety program is executed at the timing of the safety cycle time. The standard program (+ END processing) is executed
in remaining time of the safety cycle time. Therefore, if the safety program + the safety input/output processing time is long,
the execution cycle set for the FBD/LD program for process control may shift.
For the safety program and the safety cycle time, refer to the following.
( MELSEC iQ-R CPU Module User's Manual (Application))
Setting/Storage range
Low limit High limit
0 9999
Unit Initial value
s 1.00
Tag access FB
M+P_PID(_T)
M+P_2PID(_T)
M+P_2PIDH(_T)_
M+P_PIDP(_T), M+P_PIDP_EX(_T)_
M+P_IPD(_T)
M+P_BPI(_T)
M+P_R(_T)
M+P_ONF2(_T)
M+P_ONF3(_T)
M+P_MSET_
M+P_SEL_T3_
1 PROCESS CONTROL FUNCTION BLOCK
1.5 Program Execution Control
Data type Number of
digits after the
decimal point
REAL 2
1
29