Mitsubishi MELSEC LJ71C24, User Manual

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9 DATA COMMUNICATION USING THE PREDEFINED PROTOCOL
(b) When "Fixed Length/Variable Length" is "Variable Length"
An area starting from the device number which is specified on the Element
Setting 1 is considered as the data storage area.
The data storage area to be occupied varies depending on the setting of
"Unit of Stored Data".
y When "Lower Byte + Upper Byte" is selected, the same size as the
data one word (length for the data length storage area) are
occupied.
(However, when the data length of a send packet is an odd number,
the upper byte (lower byte for "Byte Swap") of the last device is not
transmitted. When the data length of a receive packet is an odd
number, one byte of 00
H
is added to the last data and stored.)
y When "Lower Bytes Only" is selected, twice size of the data
one word (length for the data length storage area) are occupied.
+1
+n
Data length storage area
*1
Send packet: Users store the send data length (data length on the line)
Receive packet: The C24 stores the receive data length (data length on the line)
*1 The unit of data length is byte.
Data storage area
Send packet: Users store the send data
Receive packet: The C24 stores the receive data
(Word)
+0
Specified device