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FX3S/FX3G/FX3GC/FX3U/FX3UC Series
Programming Manual - Basic & Applied Instruction Edition
4 Devices in Detail
4.2 I/O Relays [X, Y]
4.2.2 Functions and roles
Examples of terminal names and wiring (sink input) are for the FX3U Series PLC.
The PLC outputs signals to external loads through
output terminals. Contacts for external output
(output devices such as relay contacts, triacs and
transistors) of output relays are connected to output
terminals inside the PLC. An output relay has many
electronic NO contacts and NC contacts. These
contacts can be arbitrarily used inside the PLC.
Differences in operations between external output
contacts (output devices) and internal contacts are
explained on the next page.
The PLC receives signals from external switches
through input terminals.
An input relay (X) connected to an input terminal
inside the PLC is an electronic relay isolated
optically, and has many NO contacts and NC
contacts. These contacts can be arbitrarily used
inside the PLC.
These input relays cannot be driven by the program.
X000
X000
Y000
X001
Program example
Y000
X000
X000
PLC
Y000
Y000
NO contact
NC contact
External power
supply
Y000
COM1
Load
Output terminal
X000
0V
Input
signal
Input
terminal
24V
S/S