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CHAPTER 4 Sysway (E5 J, X format) COMMUNICATIONS PROCEDURES
E5AN/EN/CN/GN
4--2
4.1 Data Format
J
Command frame format
Commu-
nications
unit No.
Header
code
Text
@
Data
code
FCS
Termi-
nator
*
CR
FCS calculation range
@
Character (40) that indicates the start of block format
Communications
unit No.
A number within the range 0 to 99 can be set in BCD. No
response will be returned if a number other than this is set.
Header code
2-character alphabet code that indicates the command type
Data code
Set “02” only when reading and writing alarm value 2. Other-
wise, set “01”.
Text
This area stores read values, write values and status. The con-
tent of this area varies according to the command.
FCS
The FCS (Frame Check Sequence) is formed by converting the
value obtained by converting the exclusive OR of @ to the last
text character into ASCII characters.
Terminator
Indicates the end of the block format.
Comprises “*” and CR (Character Return 0D)
J
FCS calculation example
The FCS is formed by converting the 8-bit value obtained by converting
the exclusive OR of start character “@” up to the last text character into
two ASCII characters, and setting this to the FCS area.
FCS = 40H
¨
30H
¨
30H
¨
52H
¨
58H
¨
30H
¨
31H = 4BH
Start
character
@(40H)
0(30H)
0(30H)
R(52H)
X(58H)
0(30H)
1(31H)
4(34H)
B(42H)
Communications
unit No.
Header code
Data code
FCS
Calculation result 4BH is converted to ASCII at each digit and set to the FCS area.
4
!
34H
B
!
42H
The
¨
symbol indicates exclusive OR operation and the H indicates hexadecimal code.