Mitsubishi Electronics AJ65bt-r2 Manuel D’Utilisation
10 - 7
MELSEC-A
10 TROUBLESHOOTING
10.3 Examples of trouble in general-purpose input circuit
Examples of trouble that can occur in the general-purpose input circuit, and the
remedies are explained below.
remedies are explained below.
State
Cause
Remedy
Example 1
The input
signal does
not turn
OFF.
signal does
not turn
OFF.
•
Drive with LED display switch
DC input (sink)
Leakage current
Module
•
Connect an appropriate resistor so that the
voltage across the input terminal and COM1
exceeds the OFF voltage.
voltage across the input terminal and COM1
exceeds the OFF voltage.
Resistor
DC input (sink)
Module
Example 2
The input
signal does
not turn
OFF.
signal does
not turn
OFF.
•
Lead-in from use of two power supplies
E1
E2
E1>E2
DC input (sink)
Module
•
Change from two to one power supply.
•
Connect a lead-in prevention diode. (Refer
to following drawing.)
to following drawing.)
E1
E2
DC input (sink)
Module
<Example of calculating example 1>
When the LED display switch is connected to the R2, and the leakage current is
4mA
4mA
R2
3.6k
Ω
24VDC
Leakage current 4mA
Module
(1) The R2 OFF current does not satisfy 1.7mA, so it does not turn OFF. In this
case, connect a resistor as shown below.
Z
R2
24VDC
R
I
R
=1.3mA
3mA
Input impedance
3.6k
Ω
3.3k
Ω
Iz=1.7mA