FP3 MEWNET-TR
Chapter6-4. Page.92
88
6-4. Notes on 16-Bit Data Transfer
x When the I/O link function is used to transmit or receive 16-bit data, the data may not be exchanged accurately
depending on the input/output timing. When this happens, take the following programming measure.
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I/O link function of FP3 Master A and Master B
x The example shows a 16-bit data exchange using the pattern No. 11 [I/O allocation : X0 to X1F (WX0 to WX1), Y20
to Y3F (WY2 to WY3)] for both FP3 master A and master B.
x The value in data register DT0 of master A is transferred to data register DT10 of master B.
Master
station A
FP3 transmitter master unit
Master
station B
FP3/FP10S CPU
FP3 transmitter master unit
FP3/FP10S CPU
3··07··4··811
··
15 12
Bit position
11101010
DT10
11001010
3··07··4··811
··
15 12
Bit position
11101010
WX0
11001010
3··07··4··811
··
15 12
Bit position
11101010
DT0
11001010
3··07··4··811
··
15 12
Bit position
11101010
WY2
11001010
WY2
→
WX0
Slot No.1 Slot No.1
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Program example
x To ensure the accuracy of 16-bit data, an allow flag
is set using the I/O allocation of the I/O link.
The input condition when the allow flag is ON is set
for 16-bit data processing.
6-4. Notes on 16-Bit Data Transfer
R0
F0 MV, DT 0, WY 2
DF
R1
Y3F
R0 R1
Master station A
One scan
R0
R1
Y3F
WY2
X1F
R10
WX0
Master station B
R10
F0 MV, WX 0, DT10
DF
X1F
R10
One scan
Ineffective
data
Effective data
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
x The 16-bit data in data register DT0 is output from
WY2, then after one scanning cycle, a read allow
flag Y3F isoutput(X1F of the master station Bturns
ON).
x One scanning cycle after the read allow flag X1F
turns ON, the value of WX0 is transferred to data
register DT10.
x If the program is written so that the data writing
condition (in the example, R0 of master A) of the
output side turns OFF at the time an effective value
istransferred tothe data registerof theinput side(in
the example, when R10 of master B turns ON), the
values of the new data will be outputconsecutively.
x Since the accuracy of the values cannot be ensured
for the 16-bitdatawritten duringthefirst scanning
cycle of output or input, the program shown on the
left processes the values in the second and
following scanning cycles as effective data.
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Timing chart
Master station A
Master station B
Ineffective
data
Effective data
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