LG GLOFA-GM Series User Manual page 185

Chapter 7 Communication function
3) Response format(for PLC of NAK response)
Format
Name
Frame (Ex.)
ASCII value
Station number, commands, and type of command are the same as in computer request format.
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.
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
Header
Name
Frame (Ex.) ENQ
ASCII value H05
(For PLC ACK response after execution of command)
Format
Header
Name
Frame (Ex.)
ASCII value
(For PLC NAK response after execution of command)
Format
Header
Name
Frame (Ex.) NAK
ASCII value H15
Header Station No. Command
NAK H10
H15 H3130 H57(77)
Station Command
Command
No. type
H01 W(w) H16
H3031 H57(77) H3136
Station No.
ACK 01
H06 H3031
Station No. Command
H01
H3031
Command type
W(w) H02(H17)
H3032(3137)
Number Variable
Variable name
of block length
H01 H07 AAARESW
H4141415245
H3031 H3037
5357
Command Command type
W(w) H16
H57(77) H3136
Command type
W(w) H16
H57(77) H3136
7-66
Error code Tail
H1132 ETX
H31313332 H03
Number of
Data
elements
H03 HAABBCC
H414142424
H3033
343
Tail
ETX
H03
Error code Tail
Error code(2) ETX
Error code(4) H03
Frame check
BCC
Frame
Tail
check
EOT BCC
H04
Frame check
BCC
Frame check
BCC