Mitsubishi Electric MELSEC-A Manual Book page 84

6. COMMUNICATIONS IN THE BIDIRECTIONAL W O E
MELSEC-A
IRE MARKS^
Check sum
Check sum is the figures of the last
two
bytes (16 bits) of the sum of the data length and the
data area
in the text, expressed in binary data.
When 1 is set for the area for specifying check sum enabled/disabled (address 115H) of
the
buffer memory in the
A171
UC24, the check sum is not calculated.
Consequently, the text
does
not need to contain a check sum.
When not any check sum is enabled, the received data to
the
next control code (see
(1))
w i l l
be
ignored after the data area equivalent to the data length in the text is received.
This guidebook refers to data communications with the area for specifying check sum en-
abled/dkabled set to 1, and a check sum is not calculated.
For reference,
an
example of the contents of the check sum in text is given
below:
~
[Example] The check
sum
when "AJ71UC24" and the numeric value 100
are transmitted as data is as follows (unit: byte):
~
Dam
area
L
1
OAH+OOH+041 H+4AH+37H+31H+
55H+43H+32H+34H+WH+OOH
4
Sum = 025FH
02H
y
(L)
I
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