Functions And Roles - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
4.2.2

Functions and roles

Examples of terminal names and wiring (sink input) are for the FX
0V
24V
S/S
Input
signal
X000
Input
terminal
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.
90
Program example
X000
X000
Y000
X000
X000
PLC
Series PLC.
3U
X001
Y000
Y000
NO contact
Y000
NC contact
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.
4 Devices in Detail
4.2 I/O Relays [X, Y]
External power
supply
COM1
Y000
Load
Output terminal