Mitsubishi Melsec-Q Series User Manual page 475

12.5 I/O Module Troubleshooting
This section explains possible problems with I/O circuits and their corrective actions.
12.5.1 Input circuit troubleshooting
The following describes possible problems with input circuits and their corrective actions.
Condition
• Leakage current of input switch
(e.g. drive by non-contact switch).
Input signal is
not turned off.
• Drive by a limit switch with neon lamp.
Input signal is
not turned off.
• Leakage current due to line capacity of wiring cable.
(Line capacity C of twisted pair wire is approx. 100
pF/m).
Input signal is
not turned off.
• Drive by a switch with LED display.
Input signal is
not turned off.
Table12.9 Input circuit problems and corrective actions
Cause
AC input
Leakage
current
Power supply
AC input
Leakage
current
Power supply
AC input
Leakage
Input
current
module
Power supply
DC input (plus common)
Leakage current
Input
module
Table12.9 Input circuit problems and corrective actions (Continued)
• Connect an appropriate CR so that the voltage
across the terminals of the input module becomes
lower than the off voltage.
Input
module
It is recommended to use 0.1 to 47 F+47 to 120 (1/
2W) for the CR constant.
• Same as Example 1.
• Provide an independent display circuit separately.
Input
module
• Same as Example 1.
(However, leakage current is not generated when the
power supply is located in the input equipment side
as shown below.)
• Connect an appropriate resistor so that the current
across the input module becomes lower than the off
current.
*: A calculation example of the resistance to be
connected is shown on the following page.
CHAPTER12 TROUBLESHOOTING
Corrective Action
AC input
Input
R
module
AC input
Input
module
Power supply
DC input (plus common)
Input
Resister
module
12 - 180
1
2
3
12
5
6
7
8