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MELSEC-Q
8 TROUBLESHOOTING
8.2.3 When the digital output values cannot be read
Check item Corrective action
Is there any fault with the analog signal lines such as
disconnection?
Check for faulty condition of the lines visually and perform a
continuity check of the signal lines.
Is the CPU module in the STOP status? Set the CPU module to the RUN status.
Are the offset/gain settings correct?
Verify that the offset/gain settings are correct (see Sections
4.6, 5.6.2 and 5.6.3).
If the user range is being used, switch to a different default
input range and check if A/D conversion is correctly
performed. If it is correctly performed, redo the offset/gain
settings.
Is the input range setting correct?
Check buffer memory addresses 20 and 21 (Un\G20 and
Un\G21) in GX Developer system monitor.
If the input range setting is incorrect, redo the GX Developer
intelligent function module switch setting (see Section 4.5).
Is the resolution mode setting correct?
Check the ON/OFF status of the high resolution mode status
flag (X8) in GX Developer system monitor.
If the resolution mode setting is incorrect, redo the GX
Developer intelligent function module switch setting. (See
Section 4.5.)
Is the A/D conversion enable/disable setting for the channel
that was input set to A/D conversion disabled?
Check the ON/OFF status with buffer memory 0 (Un\G0) in
GX Developer system monitor and review the initial setting
of the sequence program or utility package (see Section
3.4).
Has the operating condition setting request (Y9) been
executed?
From GX Developer, set the operating condition setting
request (Y9) from ON to OFF, and check that the digital
output values are stored in buffer memory addresses 11 to
18 (Un\G11 to Un\G18). If so, review the initial setting of the
Sequence program or utility package (see Section 3.3).
POINT
The module may be faulty if the digital output values cannot be read after proper
corrective actions have been taken according to the above check items. Consult
the nearest representative or branch.