Mitsubishi QX10 - 11 I;O Module Troubleshooting; Input Circuit Troubleshooting

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MELSEC-Q
11 I/O MODULE TROUBLESHOOTING
11. I/O MODULE TROUBLESHOOTING
This chapter explains possible problems with I/O circuits and their corrective actions.
11.1 Input Circuit Troubleshooting
This section describes possible problems with input circuits and their corrective
actions.
Table 11.1 Input Circuit Problems and Corrective Actions
Condition Cause Corrective action
Example 1
An input
signal does
not turn off.
• Leakage current of input switch
(e.g. drive by non-contact switch).
Connect an appropriate resistor so that the
voltage across the terminals of the input module
will be less than the off voltage.
It is recommended to use 0.1 to 0.47 F + 47 to
120Ω (1/2W) for the CR constant.
Example 2
An input
signal does
not turn off.
• Drive by a limit switch with neon lamp.
• Same as Example 1.
• Or make up another independent display
circuit.
Example 3
An input
signal does
not turn off.
• Leakage current due to line capacity of wiring
cable.
(Line capacity C of twisted pair wire is approx.
100 pF/m).
• Same as Example 1.
• However, leakage current is not generated
when the power supply is located in the input
equipment side as shown below.
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