Reading/Writing Buffer Memory; Assigned Unit Number; 12.1.2 How To Read/Write From/To Buffer Memory - Mitsubishi FX3U-20SSC-H User Manual

FX -20SSC-H Positioning Block User's Manual
3U
12.1

Reading/Writing Buffer Memory

12.1.1 Assigned unit number

1. Assigned unit number
The unit number for the 20SSC-H is automatically assigned No.0 to No.7 starting from the special function
unit/block closest to the PLC main unit.
• In the FX FX
3U,
FX , FX
3UC
3U
(D, DS, DSS)
Main unit
• In the FX -32MT-LT, FX
3UC
Unit No.0
(built-in CC-Link/LT)
FX -32MT-LT,
3UC
FX -32MT-LT-2
3UC
Main unit

12.1.2 How to read/write from/to buffer memory

To read and write the buffer memory in the 20SSC-H, use the FROM/TO instructions or direct specification of
the buffer memory.
FX /FX PLC applicable software is required to perform direct specification of the buffer memory and bit
3U 3UC
specification of word devices.
→ For details of applied instructions, bit specification of word devices and direct specification of the
Note
Buffer memory that is assigned in 32 bits must use 32-bit instructions to read/write.
Data cannot be correctly read/written from/to buffer memory assigned in 32 bits if 16-bit read/write
instructions are used.
1. How to read and write numeric values
1) Direct specification of buffer memory
Specify the buffer memory directly as the source or destination in applied instructions, and then read or
write the contents of the buffer memory.
Unit No. (0 to 7)
a) Reading and transferring numeric values to data registers
In the program below, the contents of the buffer memory (BFM #0 and #1) in unit No. 1 are read and
transferred to data registers (D10 and D11).
Read
command
(D, DS, DSS) series
3UC
Unit No.0
Input/output
Special
extension
function block
block
-32MT-LT-2
3UC
Unit No.1
Input/output
Special
extension
function block
block
U \G
Buffer memory No. (0 to 15399)
Unit No.
Buffer memory No.
Unit No.1
Input/output
Special
extension
function block
block
Unit No.2
Input/output
Special
extension
function block
block
buffer memory, refer to the PROGRAMMING MANUAL
is substituted with a
number
FNC 12
U1\G0 D10
DMOV
12 Program Example
12.1 Reading/Writing Buffer Memory
Unit No.2
Special
function unit
Unit No.3
Special
function unit
Transfer
result
11
12
13
A
B
251