Mitsubishi FX3UC SERIES User Manual page 181

FX Series Programmable Controllers
3UC
User's Manual - Hardware Edition
6.2.5 External wiring precautions
1. Protection circuit for load short-circuits
A short-circuit at a load connected to an output terminal could cause burnout at the output element or the
PCB. To prevent this, a protection fuse should be inserted at the output.
Use a load power supply capacity that is at least 2 times larger than the total rated fuse capacity.
• External Wiring of Sink Output Type
Fuse
2. Contact protection circuit for inductive loads
The transistor output circuit in the main unit is not equipped with the internal protection circuit for the
transistor. When using an inductive load, it is recommended to use a load that has a built-in protection circuit.
When using a load that does not have a built-in protection circuit, insert a contact protection circuit on the
outside so that noise is reduced and the life is assured.
When an inductive load is connected, connect a diode (for commutation) in parallel with the load as
necessary.
The diode (for commutation) must comply with the following specifications.
Reverse voltage
Forward current
• External Wiring of Sink Output Type
Fuse
3. Interlock
For loads such as forward/reverse contactors, etc., where a hazardous condition could result if switched ON
simultaneously, an external interlock should be provided for interlocking the PLC's internal programs, as
shown to the following figure.
• External Wiring of Sink Output Type
Limit of normal
rotation
Limit of reverse
rotation
Load
0 to 7
COM1
COM1
PLC
5 to 10 times of the load voltage
Load current or more
Inductive
load
0 to 7
COM1
COM1
PLC
Interlock
PLC output
element
6 Output Specification and External Wiring
• External Wiring of Source Output Type
Load
0 to 7
Fuse
+V0
+V0
• External Wiring of Source Output Type
Inductive
load
0 to 7
Fuse
+V0
+V0
• External Wiring of Source Output Type
Interlock
Limit of normal
rotation
Limit of reverse
rotation
6.2 Transistor Output
1
2
3
PLC
4
5
6
7
PLC
8
9
PLC output
element
10
175