Device Function List - Mitsubishi Electric MELSEC-Q Structured Programming Manual

FXCPU Structured Programming Manual
[Device & Common]
1.1.2

Device function list

1. Input relay (X) and output relay (Y)
• In the PLC main unit, input relays and output relays are assigned with serial octal numbers such as "X000
to X007", "X010 to X017", "Y000 to Y007" and "Y010 to Y017".
In extension units and extension blocks, input relays and output relays are also assigned with serial octal
numbers in the connection order from the PLC main unit.
• Digital filters are used in specified input relays, and the filter value can be changed in programs.
Accordingly, assign input relay numbers having input filter for applications requiring high-speed receiving.
(Refer to explanation of filter adjustment, input interrupt, high speed counter and various instructions.)
2. Auxiliary relay (M)
• Auxiliary relays are built in the PLC. Different from input relays and output relays, auxiliary relays cannot
receive external inputs or cannot drive external loads directly.
Auxiliary relays are available only in programs.
• In some auxiliary relays, the ON/OFF status is backed up against interruption of the PLC power.
3. State relay (S)
• State relays are used as process numbers in the step ladder.
• If state relays are not used as process numbers, they can be programmed as general contacts/coils in the
same way as auxiliary relays.
• State relays can be used as annunciators for external failure diagnosis.
4. Timer (T)
• Timers count clock pulses (1 ms, 10 ms, 100 ms, etc.) inside the PLC.
When the count value reaches the set value, output contacts are activated.
Timers can measure 0.001 to 3276.7 seconds in accordance with the base clock pulse.
5. Counter (C)
Counters are classified into the following types, and can be used for suitable purposes and applications.
1) Counter (latched type)
Counters are used for signals inside the PLC. The response speed is several tens of Hz or less usually.
- 16-bit counter: For up-counting, counting range: 1 to 32767
- 32-bit counter: For up/down-counting, counting range: -2,147,483,648 to +2,147,483,647
2) High speed counter (latched type backed up against power interruption)
High speed counters can count several kHz without regard to operations in the PLC.
- 32-bit counter: For up/down-counting, counting range: -2,147,483,648 to +2,147,483,647
(1-phase 1-counting, 1-phase 2 counting or 2-phase 2 counting) assigned to specific input relays
6. Data register (D)
Data registers store numeric data.
FX PLCs have only 16-bit data registers (whose most significant bit indicates the positive or negative sign),
but two combined data registers can handle 32-bit numeric value (whose most significant bit indicates the
positive or negative sign). (Refer to "5. Counter" for the available numeric range.)
Data registers are classified into the general type and the latched type (backed up against power interruption)
in the same way as other devices.
1 Device Outline
1.1 Devices Constructing PLC
→ Refer to Section 2.2.
→ Refer to Section 2.3.
→ Refer to Section 2.4.
→ Refer to Section 2.5.
→ Refer to Section 2.6.
→ Refer to Section 2.7.
→ Refer to Section 2.8.
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