Mitsubishi Electric MELSEC-L Series - Appendix 9 Sample Program on the Connected Device Side

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(2) Non-conversion Variable
(a) Procedures
The E71 processes a Non-conversion Variable element as follows.
When the setting for "Unit of Stored Data" is "Lower Byte + Upper Byte"
• 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 sent.
• When the data length of a receive packet is an odd number, the last data is stored with one byte of 00
H
.
Ex.
When sending data whose length is an odd number
Ex.
When receiving data whose length is an odd number
When the setting for "Unit of Stored Data" is "Lower Bytes Only"
• Twice the size of the data length is occupied.
For the upper data, the E71 ignores the data at sending and adds 00
H
to the data at receiving.
03 H 04 H 01 H 02 H 05 H 06 H
04 H 03 H 02 H 01 H 06 H 05 H
0005 H
0201 H
0403 H
0605 H
+ 0
+ 1
+ 2
+ 3
Connected
device
No byte swap
(Word) Specified device
Byte swap
Sending
Data length storage area
Data storage area
Send data
↑
Data are not sent.
↓
03H02H 05H04H01H
0005H
0201H
0403H
0005H
+ 0
+ 1
+ 2
+ 3
Connected
device
Byte swap
(Word) Specified device
No byte swap
Receiving
Data length storage area
Data storage area
0005
H
0102H
0304H
0500H
+ 0
+ 1
+ 2
+ 3
(Word) Specified device
Data length storage area
Data storage area
Send data