Safety Program - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

Safety program

Safety programs are executed at every safety cycle. Safety cycle processing is performed in the order of safety input (refresh)
processing  safety program  safety output (refresh) processing. ( Page 582 Safety cycle time)
Standard programs (+ END processing) are executed within the remaining time of the safety cycle time after safety programs
are executed. (Standard programs are executed until next safety cycle time starts.)
Safety input
(input refresh)
Safety program
(operation
processing)
Safety output
(output refresh)
Standard program
Tsc: Safety cycle time
Tsio: Safety program + Safety input/output processing time
(1): Store the processing times below.
• SIL2 Process CPU: SD1890, SD1891
• SIL2 function module: Un\G62, Un\G63
(2): Execute all safety programs. (Execute safety programs A, B, and C.)
• After executing a rising/falling instruction, the instruction will be valid until the safety program for the next
safety cycle processing is executed. ( MELSEC iQ-R Programming Manual (CPU Module Instructions,
Standard Functions/Function Blocks))
• In safety programs, the block number of the file register (R) is not saved or restored. Data in the index
register (Z, LZ) are not saved or restored, either.
• Even if the operating status of SIL2 Process CPUs for which no safety program has been registered is
STOP or PAUSE, safety program operations other than operation processing are performed. Consequently,
the standard control processing time and device/label access service processing time will be longer.
35 BASIC CONCEPT
580
35.10 Running a Safety Program
Tsc
(1)
A B C (2)
Tsio
A B C
Tsio
Tsc
A B C
END
Tsio