In the process of SFC step transferring, there are some phenomena which need to pay special attention to, as the
following diagrams show.
The step S21 will be executed
at the region
93
4-1-4 Types of SFC
Based on the flow control methods of SFC, SFC has five basic types:
S0
S20
S21
S22
S23
S24
S8
S100
S101
S102
S103
S104
S21
will not be executed
will be executed
S22
B
A
:It is a Scan Time, the activated step is transferred at the scan time. Both S21 and S22 are ON at this scan time.
:Another Scan Time, it is coming after the state transfer. Although the S21 has turned OFF, it will still execute the
program within the step; meanwhile, it turns Y0 from ON to OFF.
The devices driven by the OUT instruction in the step will turn OFF (OUT Y0 in the program) for the next scan time after
the state transfer; but the devices driven by the SET instruction will remain ON (SET Y1 in the program).
S5
S10
S30S20
S21
S22
S11
S31
S32
S3
S20 S30
S31S21
S11
S9
S200
S201
S202
S203
S204
S10
S32S22
Simple Flow Selective
Branch / Merge
Simultaneously Parallel
Branch / Merge
Jump Repeat
will not be executed
will not be executed
To Next Page
Loading...
Need help?
General