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4
FUNCTIONS
4.1.4 Word data swapping function
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The high and low bytes are swapped in word units when input or output data are sent
to or received from the master station.
Use this function when the used master station handles the high and low bytes of word
data in reverse to those of the QJ71PB93D.
Data can be swapped for communication without the need for creating a program for
swapping the high and low bytes.
(1) Operation outline for swap function
The data stored in the input sending area are sent to the master station after their
high and low bytes have been swapped.
The data received from the master station are stored into the output receiving
area after their high and low bytes have been swapped.
Master station
Data 1
(L)
Input image
Data 2
(L)
Data 3
(L)
Output image
Data 4
(L)
(2) Swap function setting
The setting required for swapping I/O data, the setting by master station type and
the operation outline are described below.
(a) Swap function setting by master station type
The swap function setting changes depending on the master station type as
described below.
Master station type
When swap is not executed on
master station side (Default setting)
QJ71PB92V,
QJ71PB92D
When swap is not executed on
master station side
A1SJ71PB92D, AJ71PB92D
Other master station
Input data
Data 1
Data 1
(H)
(L)
Data 2
Data 2
(H)
(L)
Output data
Data 3
Data 3
(H)
(L)
Data 4
Data 4
(H)
(L)
PROFIBUS-DP data communication
QJ71PB93D
Data 1
(H)
Data 2
(H)
Output receiving area
Data 3
(H)
Data 4
(H)
H: High byte, L: Low byte
Swap function setting of QJ71PB93D
Disable (Not swapped)
Enable (Swapped)
Disable (Not swapped)
Set according to the specifications of
the master station
MELSEC-Q
Input sending area
Data 1
Data 1
(H)
(L)
Data 2
Data 2
(H)
(L)
Data 3
Data 3
(H)
(L)
Data 4
Data 4
(H)
(L)
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