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6. BIDIRECTIONAL
PROTOCOL
COMMUNICATIONS
MELSEC
QnA
pLiq
Checksum
Checksum is the value of the lower 2 bytes (1 6 bits) of the result (sum) addition of the data length
and data area in the message as binary data.
When the AJ71 QC24 transmission specifications checksum enable/disable switch (SW06) is set
to OFF, checksum is not handled. Therefore, the message does not have to include a sum check
code.
When checksum is not handled, when a data area of the data length in the message is received,
the receive data up to the next control code (see item
a
above) is ignored.
In this guidebook, the transmission specifications checksum enable/disable switch is set to OFF.
Therefore, checksum is not handled.
The following shows an example of the contents of the checksum in a message for your refer-
ence
~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[Example] Checksum when "AJ71 QC24" and the value 100 are send as data is shown
below. (Units: Bytes)
Computer
AJ71 QC24
025BH
' H '
D ' ,
5
' 5 1
b8
07
b l bO
memory
1
1
0
1
1
0
1
0
0
1
0
0
0
0
0
0
L
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