Omron CPM1 Programming Manual

172
Basic Ladder Diagrams Section 4-3
4-3-7 Coding Multiple Right-hand Instructions
If there is more than one right-hand instruction executed with the same execu-
tion condition, they are coded consecutively following the last condition on the
instruction line. In the following example, the last instruction line contains one
more condition that corresponds to an AND with IR 00004.
4-3-8 Branching Instruction Lines
When an instruction line branches into two or more lines, it is sometimes nec-
essary to use either interlocks or TR bits to maintain the execution condition
that existed at a branching point. This is because instruction lines are exe-
cuted across to a right-hand instruction before returning to the branching point
to execute instructions one a branch line. If a condition exists on any of the
instruction lines after the branching point, the execution condition could
change during this time making proper execution impossible. The following
diagrams illustrate this. In both diagrams, instruction 1 is executed before
returning to the branching point and moving on to the branch line leading to
instruction 2.
If, as shown in diagram A, the execution condition that existed at the branch-
ing point cannot be changed before returning to the branch line (instructions
at the far right do not change the execution condition), then the branch line will
be executed correctly and no special programming measure is required.
If, as shown in diagram B, a condition exists between the branching point and
the last instruction on the top instruction line, the execution condition at the
branching point and the execution condition after completing the top instruc-
tion line will sometimes be different, making it impossible to ensure correct
execution of the branch line.
00000 00003
00001
00004
00002
HR 0000
HR 0001
10000
10006
Address Instruction Operands
00000 LD 00000
00001 OR 00001
00002 OR 00002
00003 OR HR 0000
00004 AND 00003
00005 OUT HR 0001
00006 OUT 10000
00007 AND 00004
00008 OUT 10006
Instruction 1
00002
00000
Instruction 2
Branching
point
Instruction 1
00002
00000
Instruction 2
Branching
point
Diagram B: Incorrect Operation
Diagram A: Correct Operation
00001
Address Instruction Operands
00000 LD 00000
00001 Instruction 1
00002 AND 00002
00003 Instruction 2
Address Instruction Operands
00000 LD 00000
00001 AND 00001
00002 Instruction 1
00003 AND 00002
00004 Instruction 2

Omron CPM1 Specifications

General

Brand	Omron
Model	CPM1
Category	Controller
Language	English