Internal I/O Circuit Troubleshooting - Mitsubishi Electric Q Series User Manual

6 INSPECTION AND MAINTENANCE

6.6.4 Internal I/O circuit troubleshooting

Internal Input Circuit Troubleshooting and Corrective Action
Condition
• Drive by switch with LED indicator.
Internal input
signal is not
turned OFF.
• Sneak path due to the use of two power
supplies.
Internal input
signal is not
turned OFF.
This section describes possible problems with internal I/O circuits and their corrective
actions.
(1) Internal input circuit troubleshooting
The following describes possible problems with internal input circuits and their
corrective actions.
Cause
Leakage
current
L
E1 E2
E1>E2
<Calculation example of Example 1>
If a switch with LED display is connected to Motion controller, and current of 4
[mA] is leaked.
Leakage
current 4[mA]
3.6k[ ]
(a) Because the condition for OFF voltage (0.9[mA]) of Motion controller is not
satisfied. Connect a resistor as shown below.
3.6k[ ]
• Connect an appropriate resistor so that the
current across the Motion controller becomes
lower than the off current.
DC input
(plus common)
Motion
controller
(Note): A calculation example of the resistance to
• Use only one power supply.
• Connect a sneak path prevention diode.
DC input
(Figure below)
Motion
controller
Motion controller
Input signal
part
24VDC
Motion controller
4[mA]
Iz=0.9[mA]
Iz=3.1[mA]
R Z
Input impedance
5.6k[ ]
24VDC
6 - 31
Corrective action
Resistor
R
be connected is shown below.
L
E1 E2
DC input
(plus common)
Motion
controller
DC input
Motion
controller