34
FX
3G
/FX
3U
/FX
3UC
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 FX
3U
/FX
3UC
PLCs
FX
3U
/FX
3UC
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 (without using 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.
(The priority is given to the memory cassette.)
Built-in device memory (RAM)
[Bit device memory]
[Data memory]
T
ransfer 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)
