Mitsubishi Electric Q01UCPU User Manual page 543

(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 539, Appendix 5.4.3 (1) should be avoided, take actions described in 2) to 4).
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 is used).
<Modification example>
(Before modification)
[Ladder mode]
M0 M1
Valid
data
flag
M2
[List mode]
LD M0
LD M1
AND <> D10Z1 K5
LD M2
AND <> D10Z1 K10
ORB
ANB
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.
3) Use the index register as a local device.
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 420, Section 6.2 (3).
<> D10Z1 K5
<> D10Z1 K10
(After modification)
[Ladder mode]
M0 M1
<> D10Z1 K5
Valid data
flag
M0 M2
<> D10Z1 K10
Valid data
flag
[List mode]
LD M0
AND M1
AND <> D10Z1 K5
LD M0
AND M2
AND <> D10Z1 K10
ORB
APPENDICES
A
541