548
(2) Actions taken to avoid "OPERATION ERROR" (error code: 4101)
If the index-modified device range does not need to be checked, set the parameter as described in 1).
If the index-modified device range needs to be checked, but the detection of errors shown in Examples 2 and 3 in
Page 546, Appendix 5.4.3 (1) should be avoided, take actions described in 2) to 4).
<Modification example>
In the program before modification (on the left), the instruction immediately before the AND<> instruction is
regarded as the LD instruction. However, in the program after modification (on the right), the same instruction will
be regarded as the AND instruction.
In the program after modification, only when both contacts of M0 and M1 (or M2) turn on, the AND<> instruction is
executed. As a result, no error will be detected during index-modified device range check processing.
With a project where multiple programs are executed, to avoid the detection of "OPERATION ERROR" (error
code: 4101) both when multiple programs are executed and a particular program alone is executed, use the index
register as a local device.
Using the index register as a local device provides an independent index register for each program. Even if
another program overwrites the index register with a "value that causes the index-modified device to be outside
the device range," it will not affect the value of the index register used in the program where the error occurs with
the overwritten value. As a result, "OPERATION ERROR" (error code: 4101) will not be detected.
Note that the scan time increases because the time for saving and restoring the file register file increases. For the
local device settings, refer to Page 422, Section 6.2 (3).
1) Deselect the "Check Device Range at Indexing" item in the PLC RAS tab of the PLC parameter dialog
box so that the index-modified device range will not be checked.
2) As shown in the following modification example, connect the valid data flag contact in series for each
instruction that performs the index-modified device range check processing (except when a High-
speed Universal model QCPU and Universal model Process CPU are used).
3) Use the index register as a local device.
M0
(After modification)
(Before modification)
[Ladder mode]
[Ladder mode]
[List mode]
[List mode]
M0
M0
M1
M1
M2
M2
Valid
data
flag
LD
M0
LD
M1
AND <>
D10Z1
K5
LD
M2
AND <>
D10Z1
K10
ORB
ANB
<> D10Z1 K5
<> D10Z1 K10
<> D10Z1 K5
<> D10Z1 K10
Valid data
flag
Valid data
flag
LD
M0
AND
M1
AND <>
D10Z1
K5
LD
M0
AND
M2
AND <>
D10Z1
K10
ORB
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