Step Transition Bit - Mitsubishi MELSEC-Q Series Programming Manual

4 SFC PROGRAM CONFIGURATION

4.5.2 Step transition bit

The step transition bit is designed to check whether the transition condition of the step in
execution has been satisfied or not.
(1) After the operation output at each step is completed, the step transition bit automatically
switches ON when the transition condition (for transition to the next step) is satisfied.
(2) A transition bit which is ON will automatically switch OFF when processing of the block in
question occurs again.
Example: Step transition bit = M1
Block "n"
S0
(Transition condition 0)
S1
(Transition condition 1)
S2
(Transition condition 2)
S3
(3) If a continuous transition is designated (continuous transition bit ON), the transition bit will
remain ON during the next step's operation output after the transition condition is satisfied.
It will also remain ON following the execution of multiple steps, even if the transition condition
is unsatisfied.
In these cases, the transition bit will switch OFF when block execution occurs at the next scan.
Example: Step transition bit = M1
4 - 75
ON
"M1"
OFF
ON
"M1"
OFF
4 - 75