Extension Register [R] And Extension File Register [Er]; Numbers Of Extension Registers And Extension File Registers; Data Storage Destination And Access Method - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
4.10

Extension Register [R] and Extension File Register [ER]

Extension registers (R) are the extended form of data registers (D).
The contents of extension registers (R) can be stored in extension file registers (ER). In FX
extension file registers (ER) are available only while the memory cassette is attached.

4.10.1 Numbers of extension registers and extension file registers

The table below shows numbers of extension registers (R) and extension file registers (ER).
(Numbers are assigned in decimal.)
1. FX /FX PLC
3U 3UC
Extension register (R)
(latched [battery backed] type)
R0 to R32767
32768 points
2. FX PLCs
3G
Extension register (R)
(General type)
R0 to R23999
24000 points
*1. Available only while a memory cassette is mounted (because they are stored in the flash memory
inside a memory cassette.)
*2. These registers can be changed to the latched (battery backed) type by the parameter setting when
the optional battery is used. However, the latched range cannot be set.
*3. These registers are stored in the EEPROM built in the PLC, or in the EEPROM in the memory
cassette when the memory cassette is attached.

4.10.2 Data storage destination and access method

Because the memory for storing data is different between extension registers and extension file registers, the
access method is different as shown in the table below:
Data storage destination
Device
Extension register
Extension file register
Difference in the access method
Reading in program
Writing in program
Display module
Test operation in online mode of GX Developer
Data change
Batch writing by GX Developer
method
Computer link function
*2
PLC
FX /FX Built-in RAM (latched [battery backed] area)
3U 3UC
FX Built-in RAM
3G
FX /FX Memory cassette (flash memory)
3U 3UC
FX Built-in EEPROM or EEPROM in memory cassette
3G
Access method
4.10 Extension Register [R] and Extension File Register [ER]
Extension file register (ER)
(file type)
ER0 to ER32767
*1
32768 points
Extension file register (ER)
(file type)
ER0 to ER23999
*3
24000 points
Data storage destination
Extension
register
4 Devices in Detail
/FX PLCs,
3U 3UC
Extension file register
Only dedicated instructions
are enabled
Only dedicated instructions
are enabled
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×
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