Errors Occurring In The Output Circuit And Corrective Actions - Mitsubishi Electric CC-Link User Manual

6 TROUBLESHOOTING

6.2.2 Errors occurring in the output circuit and corrective actions

Condition
Whegn the external
power supply turns on,
Example 1
the load turns on for a
moment.
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Examples of errors that occur in the output circuit and corrective actions are explained
below:
Erroneous output due to the stray capacitance (C)
between collector and emitter of hotocoupler.
There is no erroneous output at normal road.
An erroneous output may occur at high
sensitivity load (such as solid state relay).
Output module, Combined module
Photocoupler
C
Ic
Constant
voltage circuit
If the external power supply is turned on precipitously,
Ic urrent flows due to the stray capacitance (C)
between collector and emitter of hotocoupler.
Ic current flows to the next stage of transister Tr1 gate
and Y0 utput turns on by 100 s
SW: External power
supply (24V) at On
Output Y0
Cause
Tr1
Y0
CTL+
SW
COM-
24V
10ms or less
Approx. 100 s
MELSEC-A
Corrective action
When the external power turns ON/OFF,
check that the external power supply rising
edge must be 10ms or more, and switch the
SW1 to the primary side of external power
supply.
Primary
side
external power supply
SW1
When switching to the secondary side of
the external power supply is required, the
external power supply rising edge
connected a condenser must be slow, and
measured 10ms or more.
Y0
R1
CTL+
C1
COM-
24V
R1: Several tens of ohms
Power capacity (external power supply
*1
current )
resistance value
*2
(3 to 5)
C1: Several hundreds of microfarads F 50V
*1 Refer to consumption current of the
external power supply for modules used in
this manual.
*2 Select the power capacity of resistance
to be 3 to 5 times lager than the actual
power consumption.
(Example)
R1=40 , C1=300 F
Use the below expression to calculated a
time constant
-6
C1 R1=300 10 40
-3
=12 10 s
=12ms
Secondary
side
PLC
SW
2
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