LG GLOFA-GM Series User Manual page 133

Chapter 7 Communication function
STX/ETX as of control characters of ASCII code are used for Header and Tail.
'RD' command is used as Read command.
24 byte of Read data is displayed using '24' in data length area.
24 byte data is sent to data area.
BCC calculates ASCII code values from Header to Tail as added in HEX., however changeable with the
variable data area per frame.
C) [Table7.8] shows the structure of Immediate response frame. Immediate response frame as of response
frame correspondent to Read frame responds to the received command without data.
[Table7.8] Structure of Immediate response frame
Trans. sequence
Frame type
Transmission frame
ASCII code
ACK/ETX as of control characters of ASCII code are used for Header and Tail.
Received command 'RD' is sent again.
Received data length '24' is sent again.
No BCC.
2) User defined programming
Procedure sequence in GLOFA-PLC for communication via the protocol of other company's PLC in user mode is
as follows.
① Set Cnet I/F module to user defined mode.
② Define TX/RX frame via Frame Editor as agreed with other company's protocol. And set basic
parameters as communication speed, etc. also to be agreed with the specification of other company's
communication.
③ If Frame Editor is prepared, let it downloaded to Cnet I/F module and then run communication.
④ Prepare program which can transmit/receive frame via GMWIN, let it downloaded to PLC CPU and then
check the result via program monitor.
Header
Header
ACK
H10
[Note]
Frame body
Command(CONST)
R D
H52 H44
7-14
2 4
H32 H34
Tail
Tail
ETX
H03