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FX3S/FX3G/FX3GC/FX3U/FX3UC Series
Programming Manual - Basic & Applied Instruction Edition
2 Overview (Sequence Program)
2.5 Introduction of Devices Constructing PLC
2.5 Introduction of Devices Constructing PLC
Many relays, timers, and counters are built into an FX3S/FX3G/FX3GC/FX3U/FX3UC PLCs, with many NO (normally
open) contacts and NC (normally closed) contacts.
These contacts and coils are connected to make a sequence circuit.
A PLC is also equipped with data registers (D) and extension data registers (R) functioning as memory devices to
store numeric data values.
2.5.1 Relationship among devices
Arrows show transfer of signals.
4123
Input terminal or
input connector
Input relay: X
Input relays function as receiving ports when the PLC receives signals from external
input switches.
The assigned device mnemonic is "X".
The PLC has built-in input relays in accordance with its size.
Auxiliary relay: M
There are many
auxiliary relays
inside the PLC.
The assigned
device mnemonic
is "M".
State relay: S
There are many
state relays inside
the PLC.
The assigned
device mnemonic
is "S".
Timer: T
There are many
timers inside the
PLC.
The assigned
device mnemonic
is "T".
Counter: C
There are many
counters inside the
PLC.
The assigned
device mnemonic
is "C".
Output relay: Y
Output relays
function as ports
when the PLC
drives external
loads.
There are many
output relays inside
the PLC.
The assigned
device mnemonic
is "Y".
Output terminal
or output
connector
Contact for external output from output relay
(one normally open contact)
The PLC has built-in output contacts in accordance with its
size.