Chapter 13. Dedicated Cnet communication for GM6
13 - 4
13.4
Frame structure
1) Basic structure of frame
(1) Request frame(external communication devices
→
Cnet module)
(Max. 256 Bytes)
Header
(ENQ)
Station
No.
Command
Type of
command
Structurized data area
Tail
(EOT)
Frame
check(BCC)
(2) ACK response frame(Cnet module
→
external communication devices, when data is normally received)
(Max. 256 Bytes)
Header
(ENQ)
Station
No.
Command
Type of
command Structurized data area or null
Tail
(ETX)
Frame
check(BCC)
(3) NAK response frame(Cnet module
→
external communication devices, when data is abnormally received)
(Max. 256 Bytes)
Header
(NAK)
Station
No.
Command
Type of
command
Error code (ASCII 4 Bytes)
Tail
(ETX)
Frame
check(BCC)
Table 13.1 Control characters
Code
Hex value
Original word
Contents
ENQ(Header)
H05
Enquire
Start code of request frame
ACK(Header)
H06
Acknowledge
Start code of ACK response frame
NAK(Header)
H15
Not acknowledge
Start code of NAK response frame
EOT(Tail)
H04
End of text
End ASCII code of request frame
ETX(Tail)
H03
End Text
End ASCII code of response frame
The contents of the code used are as below Table. Control characters are importantly used during serial
communication, so they must be well acquainted.
Remark
