Chapter 8. Communication Functions
8-22
(4) GM7U main unit response format (NAK response)
Format name Header
Station
No.
Command
Registration No.
Error code
(Hex 2Byte)
Tail Frame check
Frame NAK
H10 Y(y) H09 H1132 ETX BCC
ASCII value H15 H3130 H59(79) H3039 H31313332 H03
Item Description
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 assumes that registered device no. 1 at station no. 1 is read, and the BCC value is checked. It is also
assumed that the device %MW0 is registered and the number of blocks is 1.
① PC request format (PC → GM7U main unit)
Format name Header
Station
No.
Command
Registration No. Tail Frame check
Frame (Ex.) ENQ H01 Y H01 EOT BCC
ASCII value H05 H3031 H79 H3031 H04
② For ACK response after execution of command (PC → GM7U main unit)
Format name Header
Station
No.
Command
Registration
No.
Number of
Blocks
Number of
data
Data Tail Frame check
Frame ACK H01 y H01 H01 H04 H23422339 ETX BCC
ASCII
value
H06 H3031 H79 H3031 H3031
H3034
H3233343232333339 H03
③ For NAK response after execution of command (PC → GM7U main unit)
Format name Header
Station
No.
Command
Registration No. Error code Tail Frame check
Frame (Ex.) NAK H01 y H01 Error code (2) ETX BCC
ASCII value H15 H3031 H79 H3031 Error code(4) H03
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