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Chapter 7 Communication function
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3) Response format(for PLC of NAK response)
Format
Name
Header Station No. Command Command type Error code Tail Frame check
Frame (Ex.) NAK H10 W(w) H02(H17) H1132 ETX BCC
ASCII value H15 H3130 H57(77) H3032(3137) H31313332 H03
9 Station number, commands, and type of command are the same as in computer request format.
9 BCC : When command is one of lower case(w), only one lower byte of the value resulted by adding 1 byte
each to ASCII values from NAK to ETX is converted into ASCII, added to BCC, and sent.
9 Error code is HEX and 2 bytes(ASCII code, 4 bytes), which indicates type of error. For the details, see
Appendix ‘B. Error Code Table’.
4) Example of use
In case HAABBCC is written in variable name of “AAARESW” with data type of Array byte[0] ~ [2] in station No.1.
(Computer request format)
Format
Name
Header
Station
No.
Command
Command
type
Number
of block
Variable
length
Variable name
Number of
elements
Data Tail
Frame
check
Frame (Ex.) ENQ H01 W(w) H16 H01 H07 AAARESW H03 HAABBCC EOT BCC
ASCII value H05 H3031 H57(77) H3136 H3031 H3037
H4141415245
5357
H3033
H414142424
343
H04
(For PLC ACK response after execution of command)
Format
Name
Header Station No. Command Command type Tail Frame check
Frame (Ex.) ACK 01 W(w) H16 ETX BCC
ASCII value H06 H3031 H57(77) H3136 H03
(For PLC NAK response after execution of command)
Format
Name
Header Station No. Command Command type Error code Tail Frame check
Frame (Ex.) NAK H01 W(w) H16 Error code(2) ETX BCC
ASCII value H15 H3031 H57(77) H3136 Error code(4) H03