512
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
19 Data Operation 2 – FNC140 to FNC149
19.2 FNC141 – WTOB / WORD to BYTE
3) When "n" is an odd number, only the low-order byte (8 bits) of the final one among the separation source
devices is regarded as the target data as shown in the figure below.
For example, when "n" is "5", the data from
to the low-order byte (8 bits) of
+2 is stored in
to
+4.
4) When "n" is "0", WTOB instruction is not executed.
Related instruction
Caution
Devices storing the separation source data can overlap devices storing the separated data.
When "n" is an odd number, however, the high-order byte (8 bits) of the final data of the separation source is
overwritten and erased.
Errors
An operation error is caused in the following cases; The error flag M8067 turns ON, and the error code is
stored in D8067.
• When the separation source devices
to
+n/2 are outside the specified device range (error
code: K6706)
When "n" is an odd number, the number of a rounded up value decides the number of devices. (error
code: K6706)
• When the separated data destination devices
to
+n-1 are outside the specified device range
(error code: K6706)
Program example
In the program shown below, the data stored in D10 to D12 is separated in units of byte, and stored in D20 to
D25.
Instruction
Description
BTOW (FNC142)
Combines the low-order 8 bits (low-order byte) of consecutive 16-bit data.
S
S
D
D
b15
b8 b7
b0
S
+0
+1
+2
It is ignored when
"n" is "5".
D
+0
+1
"H00" is stored.
+2
+3
+4
When "n"
is "5"
12H
56H
FEH
39H
78H
DCH
00H
00H
39H
12H
00H
00H
78H
56H
00H
DCH
b15
b8 b7
b0
S
=D12
It is ignored when "n" is "5".
Because D14, the final one among the
separation source devices and
later, is included in the separation result
destination devices and later,
"36H" is overwritten and erased.
D
=D12
D13
"H00" is stored.
When "n"
is "5"
32H
34H
36H
31H
33H
35H
00H
00H
31H
32H
00H
00H
33H
34H
00H
35H
D13
D14
D
S
D14
D15
D16
b15
b8 b7
b0
b15
b8 b7
b0
S
S
D
D
X000
FNC141
WTOBP
D10
D20
K6
END
D10
D20
D21
6 bytes
FDH
57H
34H
58H
E2H
44H
00H
00H
58H
FDH
00H
00H
E2H
57H
00H
44H
D11
D12
D22
D23
D24
00H
34H
D25
b15
b8 b7
b0
b15
b8 b7
b0
"H00" is stored.
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