Mitsubishi Electric MELSEC-Q Series Programming Manual page 117

• The continuous transition disable flag (SM324) is always ON (turned ON automatically by the system at SFC program
execution) normally, but is OFF during continuous transition. Use of SM324 under the AND condition in a transition
condition disables a continuous transition.
Ex.
[SFC program]
[Operation]
1.
When M0 is ON, step 1 to step 4 are the targets of continuous transition.
2.
Since SM324 is added as the AND condition to the transition condition following step 3, the transition condition following
step 3 is not satisfied after execution of step 3.
3.
When step 3 is executed in the next scan, execution proceeds to step 4 in the same scan since SM324 is ON.
• When a jump transition or selection coupling causes a transition from multiple steps to one step, the
operation output of one step may be executed twice in a single scan. When the setting is "with continuous
transition" in the case as shown above, execution passes through step 3 twice in a single scan.
• In the case of "with continuous transition", a step start/end is made within one scan. Since the END
processing is not executed in this case, the coil output turned on by the OUT instruction in the operation
output is not reflected on the device. When the coil output is the Y output, actual output is not provided. In
addition, ON of the step relay cannot be detected.
• In the case of a program that uses a jump transition for looping, care must be taken when the transition
conditions in the loop are all satisfied during execution at the "with continuous transition" setting, since an
endless loop will occur within one scan, resulting in WDT Err. (No. 5001).
4 SFC PROGRAM CONFIGURATION
4.5 SFC Information Devices
4
115