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FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
2 Overview (Sequence Program)
2.6 Program Memory and Devices
2.6 Program Memory and Devices
2.6.1 Memory structure
1. In FX3U/FX3UC PLCs
FX3U/FX3UC PLCs are equipped with the RAM memory as standard.
By mounting a memory cassette, the memory type can be changed.
1) When using the built-in memory (without attached memory cassette)
2) When using an attached memory cassette (dose not use the built-in program memory)
CPU System ROM
Built-in program memory
(RAM)
Parameter
File register (D)
Comment
Sequence program
Memory cassette
(Flash memory)
Not attached
Built-in device memory (RAM)
[Bit device memory]
• Data register (D)
• Timer present value register (T)
• Counter present value register (C)
• Index register (V, Z)
Contact image memory
• Input relay (X) • Output relay (Y)
• Auxiliary relay (M) • State relay (S)
Timer contact and time counting coil
Counter contact, counting coil, and reset coil
• Extension register (R)
[Data memory]
CPU System ROM
Built-in program memory
(RAM)
Not used
Memory cassette
(Flash memory)
Parameter
File register (D)
Comment
Sequence program
Extension file register (ER)
The PLC automatically recognizes attachment of a
memory cassette (when the power is turned ON),
and disconnects the built-on program memory.
(Priority is given to the memory cassette.)
Built-in device memory (RAM)
[Bit device memory] [Data memory]
Transfer and initialization by
instructions
Contact image memory
• Input relay (X) • Output relay (Y)
• Auxiliary relay (M) • State relay (S)
Timer contact and time counting coil
Counter contact, counting coil, and reset coil
• Data register (D)
• Timer present value register (T)
• Counter present value register (C)
• Index register (V, Z)
• Extension register (R)