Chapter 12 Troubleshooting MASTER-K
12-8
12.4 Troubleshooting examples
This chapter shows some typical examples
12.4.1 Input circuit troubles and corrective actions
Condition Cause Corrective Action
Input signal
does not
turn OFF
Leakage current of external device (such
as a drive by non-contact switch)
Input signal
does not
turn OFF
Leakage current of external device (Drive
by a limit switch with neon lamp)
• Connect an appropriate register and
capacity which will make the voltage across
the terminals of the input module lower than
• C and R values are determined by the
leakage current value
- Reminded value C : 0.1 ~ 0.47uF
R : 47 ~ 120Ω (1/2W)
Or make up another independent display
circuit
Input signal
does not
turn OFF
Leakage current due to line capacity of
wiring cable
• Power supply is located on the external
device side as shown below
Input signal
does not
turn OFF
Leakage current of external device (Drive
by switch with LED indicator)
• Connect an appropriate register which will
make the voltage across input module
terminal and common higher than the OFF
voltage, as shown below
Input signal
does not
turn OFF
• Sneak current due to the use of two
different power supplies
• E1 > E2, Sneak current
• Use only one power supply
• Connect a sneak current prevention
diode(Figure below)
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