Fnc 79 - To / Write To A Special Function Block - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
15.10 FNC 79 – TO / Write To A Special Function Block
Outline
This instruction writes data from a PLC to buffer memories (BFM) in a special extension unit/block.
When a large capacity of data is written to buffer memories (BFM) by this instruction, a watchdog timer error
may occur. When splitting the data to be written does not affect the control, use WBFM (FNC279) instruction.
1. Instruction format
FNC 79
D TO
2. Set data
Operand Type
m1
m2
S
n
3. Applicable devices
Bit Devices
Oper-
and System User
Type
X Y M T C S D .b KnX KnY KnM KnS T C D R U \G
m1
m2
S
n
Explanation of function and operation
1. 16-bit operation (TO and TOP)
PLC (word device) → Special extension unit/block (BFM)
"n"-point 16-bit data starting from
starting from the buffer memory (BFM) # m2 inside a special extension unit/block No. m1.
Command
input
FNC 79
472
Mnemonic
16-bit Instruction
P
TO
9 steps
TOP
Unit number of a special extension unit/block
(K0 to K7 from the right side of the main unit)
Transfer destination buffer memory (BFM) number
Device number storing the transfer source data
Number of transfer points
Digit Specification
→ For the common items between FROM instruction and TO instruction,
S
m1 m2
TO
15 External FX I/O Device – FNC 70 to FNC 79
15.10 FNC 79 – TO / Write To A Special Function Block
→ For WBFM (FNC279) instruction, refer to Section 31.2.
Operation Condition
32-bit Instruction
Continuous
Operation
Pulse (Single)
Operation
Description
Word Devices
Special
System User
Unit
inside a PLC are transferred (written) to "n"-point buffer memories
S n
Number of transfer points
n = 1 to 32767
Transfer source (PLC)
Transfer destination (Special
extension unit/block) BFM #
m2 = 0 to 32766
Unit No.
m1 = 0 to 7
Mnemonic Operation Condition
DTO
17 steps
DTOP
16- or 32-bit binary
16- or 32-bit binary
16- or 32-bit binary
16- or 32-bit binary
Others
Con- Real
Index
stant Number
V Z Modify K H E
refer to Subsection 15.9.1.
Continuous
Operation
Pulse (Single)
Operation
Data Type
Charac-
Pointer
ter String
" " P