110
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
4 Devices in Detail
4.9 Extension Register [R] and Extension File Register [ER]
4.9
Extension Register [R] and Extension File Register [ER]
Extension registers (R) are devices for extending data registers (D), and are backed up by the battery.
While a memory cassette is mounted, the contents of extension registers (R) can be stored in extension file
registers (ER). However, extension file registers (ER) are available only while a memory cassette is
mounted.
4.9.1
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.
Available only while a memory cassette is mounted (because they are stored in the flash memory
inside a memory cassette.)
4.9.2
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
Difference in the access method
Extension register (R)
(latched [battery backed] type)
Extension file register (ER)
(file type)
FX
3U
/FX
3UC
PLC
R0 to R32767
32768 points
ER0 to ER32767
32768 points
*1
Device
Data storage destination
Extension register
Built-in RAM (latched [battery backed] area)
Extension file register
Memory cassette (flash memory)
Access method
Extension
register
Extension file register
Reading in program
3
U
Only dedicated instructions
are enabled
Writing in program
3
U
Only dedicated instructions
are enabled
Display module
3
3
Data change
method
Test operation in online mode of GX Developer
3
×
Batch writing by GX Developer
3
3
Computer link function
3
×
