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8. COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
(7)
Sum check code
The sum check code is 2-digit ASCll representing the lower 1 byte (8
bits) of the sum derived from the BIN code representing the checked
data.
With DIP switch SW21 OFF, the sum check code is not added
Example: If A,B,C, and D are transferred in format 1, setting station
number 0, PC CPU number FF, command BR (batch read of
device memory), and message wait time to
30
msec, the sum
check code value is as shown below
I
St. No.
: Station
number
Computer
(8)
Error code
0
Indicates an error following a NAK transmission
*Error codes are transmitted as 2-digit ASCll (hexadecimal) in the
range of OOH to FFH.
*If two or more errors occur simultaneously, the error code of the
lowest number is transmitted.
Q
05H
l
For error code details, see Section 11 . I .
I
,
. O .
. O .
30H/30H
I
"F . ?
46H146H
I
Command
'8'
'w
42H152H
! : E g
33H
I
I
I
Characten
area
. n .
. s .
.c. .o.
41H142H(43H144H
I
zgM
code
.s. .o"
42H144H
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