Fault Examples With I/O Modules; Faults With The Input Circuit And The Corrective Actions - Mitsubishi Q2ACPU User Manual

22. TROUBLESHOOTING

22.5 Fault Examples with I/O Modules

Examples of faults concerning I/O circuits and the corrective actions are explained.

22.5.1 Faults with the input circuit and the corrective actions

Examples of faults concerning input circuit and the corrective actions are explained.
Situation
Input signal does not
turn OFF.
Input signal does not
turn OFF.
Input signal does not
turn OFF.
Input signal does not
turn OFF.
Faults with the input circuit and the corrective actions
Cause
• Leak current from input switch
(driven by a contactless switch, etc.)
• Driven by a limit switch with a neon lamp
• Line capacity C of the leak current
twisted pair cable due to line capacity
of the wiring cable is about 100PF/m.
• Driven by a switch with LED indication
• Connect an appropriate resistance so that voltage
between the terminals of the input module is
lower than the OFF voltage.
For CR constant,
0.1 to 0.47
recommended.
• Same as the example 1.
• Or, provide a totally independent display circuit
separately.
• Same as the example 1.
• However, leakage current does not occur when a
power supply is on the side of input device as
shown below.
• Connect an appropriate resistance so that voltage
between the terminal of the input module and the
common is lower than the OFF voltage as shown
below.
* An example of calculation of resistor to be
connected is provided on the following page.
22 - 47
Countermeasure
F + 47 to 120 (1/2W) is