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11 TROUBLESHOOTING
11.4 Examples of Troubles with the I/O Module
When the output module is off, the LED connected as a load dimly turns on
■Cause
The load operates by the leakage current when the output module is off.
■Action
Connect a resistor of 5 to 50k in parallel with the LED load.
When a digital display unit is connected as a load, the display may not be normal
■Cause
The load operates by the leakage current when the output module is off.
■Action
Install a pull-up resistor of 5 to 50k and 0.5 (W) between the outputs of 24VDC power supply and the output module.
LED
COM-
Y0
Output module
24VDC
Countermeasure
Sink output
Y0
CTL+
COM-
Digital display unit
(input signal section)
Countermeasure
24VDC
Output module
Dedicated IC
Sink output
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