Omron SYSMAC C20P Operation Manual page 46

The Ladder Diagram
38
Clear instructions would not affect execution. If 0000 is OFF, the Interlock
instruction would produce an OFF execution condition for instructions 1 and
2 and then execution would continue with the instruction line following the
Interlock Clear instruction.
As shown in the following diagram, more than one Interlock instruction can
be used within one instruction block; each is effective from its branching point
through the next Interlock Clear instruction.
IL(02)
0000
0002
If 0000 in the above diagram was OFF (i.e., if the execution condition for the
first Interlock instruction was OFF), instructions 1 through 4 would be exe-
cuted with OFF execution conditions and execution would move to the in-
struction following the Interlock Clear instruction. If 0000 was ON, the status
of 0001 would be loaded to form the execution condition for instruction 1 and
then the status of 0002 would be loaded to form the first execution status for
that instruction line, i.e., the execution condition for the second Interlock in-
struction. If 0002 was OFF, instructions 2 through 4 would be executed with
OFF execution conditions. If 0002 was ON, 0003, 0005, and 0006 would
each start a new instruction line.
Because all branch lines following branching points with Interlock instructions
form independent instruction lines, interlocked sections of programs can be
redrawn without branching points. The following diagram executes exactly
like the one above and would be input in exactly the same order using the
same instructions.
0000
0001
0002
0003 0004
0005
0006
This type of interlock diagram appears when inputting ladder diagrams di-
rectly, as is possible from a GPC.
0001
IL(02)
0003 0004
0005
0006
Section 4–3
Instruction 1
Instruction 2
Instruction 3
Instruction 4
ILC(03)
IL(02)
Instruction 1
IL(02)
Instruction 2
Instruction 3
Instruction 4
ILC(03)