When A Disconnection In The Input Wiring Cannot Be Detected; When A Disconnection In The Input Wiring Cannot Be Detected Correctly; When A Disconnection Was Detected In The Input Wiring - Mitsubishi Electric MELSEC iQ-RX40NC6B Application User's Manual

When a disconnection in the input wiring cannot be detected

Check item
Check whether the I/O status indicator LED (X0 to XF) of the input module
with diagnostic functions turns on when the external input device is on.
Check whether "Input disconnection detection setting" has been set to "To
detect".
Check whether a resistor for disconnection detection has been connected.
Check whether the disconnection (no connection) detection current satisfies
the specifications.
If a disconnection in the input wiring still cannot be detected even after the actions described above are taken,
the possible cause is a failure of the input module with diagnostic functions. Please consult your local
Mitsubishi representative.
When a disconnection in the input wiring cannot be detected
correctly
Check item
Check whether the wiring is influenced by noise.
Check whether a wireless communication device such as a cellular phone or
PHS (Personal Handy-phone System) is close to the programmable controller.

When a disconnection was detected in the input wiring

Check item
Check whether the input wiring has any problems.
Check whether the external power supply is supplied.
Check whether the wiring is influenced by noise.
Action
When the LED does not turn on, the input wiring has problems.
Check whether the input wiring has been disconnected or short-circuited and
the voltage of the input signal is proper, and review the wiring.
For the rated input voltage, refer to the performance specifications described
in the following.
 MELSEC iQ-R I/O Module (With Diagnostic Functions) User's Manual
(Startup)
If "Input disconnection detection setting" of the target input has been set to
"Not detected", set "To detect".
When the leakage current of the input device is 0.3mA/point or lower, connect
a bleeder resistor (resistance value as a guide: approximately 56k) in
parallel near the input device.
Check whether the disconnection (no connection) detection current is 0.3mA
per point or less.
Action
Check the wiring status.
Use any wireless communication device such as a cellular phone or PHS
(Personal Handy-phone System) more than 25cm away in all directions from
the programmable controller.
Action
Check that the voltage of the input signal is proper, and review the wiring.
Check that the supply voltage to the module is within the rated range.
Check the wiring status.
3.3 Troubleshooting by Symptom
3 TROUBLESHOOTING
3
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