Step Run and Break Section 4-3
105
4-3-4 Start Point Setting
Setting a start point enables to specify an instruction to be executed next by
the program.
Start Point Setting
A start point can be set only in the Program mode. The program is executed
from the start point when an execution is operated from the Debug Console
or the mode is changed to the Monitor mode by the CX-Programmer. For ex-
ample, executing Step Run with a start point specified will move the execution
control to the start point and begin the next Step Run.
Start Point Location
If a start point is set halfway in the rung, the previous value of power flow
turns OFF (false) forcibly regardless of the present value. For example, set-
ting a start point at the right hatched part in the diagram below will not exe-
cute the rung, which originally would be executed, because the power flow is
forcibly turned OFF.
When executing the diagram with a start point set, set the start point at the
top of the rung (the left hatched part in the diagram).
Program
address
Instruction word
(Mnemonic)
Operand
000000 LD 000000
000001 AND 000001
000002 LD 000002
000003 AND NOT 000003
000004 LD NOT 000100
000005 AND 000101
000006 OR LD
000007 AND LD
000008 OUT 000200
000009 END
Note Be careful when setting a start point in JUMP instructions or a loop rung as
shown below. Doing so may cause an unstable JUMP address and an unex-
pected operation.
· Setting within a subroutine
· Setting within a FOR to NEXT loop
· Setting within a block program
Looping may fail (exit the loop unexpectedly) because the loop condition is not
evaluated correctly. For JUMP instructions (including subroutines), the JUMP
destination address when the JUMP instruction was last executed will be exe-
cuted or an instruction error will occur. If an instruction error occurs, once stop
the program or set to the Program mode and then resume the operation.
Note Refer to 2-1 Basic Concepts of CS/CJ Series Programming Manual (W394)
for the power flow.
0000
00
0000
01
0000
02
0000
03
0002
00
0001
00
0001
01
END
Power flow
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