LS Industrial Systems GLOFA G7M-DR20U/DC - Page 250

Chapter 8. Communication Functions
8-24
(4) GM7U main unit response format (NAK response)
Format name Header
Station
No.
Command Command type
Error code
(Hex 2 Byte)
Tail Frame check
Frame (Ex.) NAK H0A R(r) ST H1132 ETX BCC
ASCII value 15 3041 5272 5354 31313332 03
Item Description
Frame check
(BCC)
When the command is lowercase(r), only one lower byte of the value resulted by adding 1 Byte each
to the ASCII values from NAK to ETX is converted into ASCII and added to BCC, and then sent.
Error code Hex and 2 bytes (ASCII code, 4 bytes) indicate error type. For the details, see 8.1.8 Error codes.
(5) Example
This example supposes that the status of GM7U Main unit of station no. 1 is read.
① Computer request Format (PC → GM7U Main Unit)
Format name Header
Station
No.
Command Command type Tail Frame check
Frame (Example) ENQ H01 R(r) ST EOT BCC
ASCII value H05 H3031 H52(72) H5354 H04
② For ACK response after execution of command (PC ← GM7U Main Unit)
Format name Header
Station
No.
Command Command type Status data Tail
Frame check
Frame (Example) ACK H01 R(r) ST
See status
data format
ETX BCC
ASCII value H06 H3031 H52(72) H5354 H03
③ For NAK response after execution of command (PC ← GM7U Main Unit)
Format name Header
Station
No.
Command Command type Error code Tail
Frame check
Frame (Example) NAK H01 R(r) ST Error code (2) ETX BCC
ASCII value H15 H3031 H52(72) H5354 Error code (4) H03