Chapter 8. Communication Functions
8-14
(3) 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 H10 r SB H1132 ETX BCC
ASCII value H15 H3130 H72 H5342 H31313332 H03
Item Description
Error code Hex and 2 bytes (ASCII code, 4 bytes) indicate error type. For the details, see 8.1.8 Error codes.
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.
(3) Example
• This example assumes that 2 Double words from %MD0 of station no.10 is read.
(In this case, H12345678 is in %MD0 and H9ABCDEF0 is in %MD1)
① PC request format (PC → GM7U main unit)
Format name Header Station No. Command
Command
type
Data
length
Variable name
Number of
data
Tail
Frame
check
Frame (Ex.) ENQ
H0A r SB H04 %MD0 H02 EOT BCC
ASCII value H05
H3041 H72 H5342 H3034
H254D4430 H3032 H04
② For ACK response after execution of command (PC ← GM7U main unit)
Format name Header Station No. Command
Command
type
Number of data
Data Tail
Frame
check
Frame (Ex.) ACK
H0A r SB H08 12345678 9ABCDEF0 ETX BCC
ASCII value H06
H3041 H72 H5342 H3038
H31323334353637383
941424344454630
H03
③ For NAK response after execution of command (PC ← GM7U main unit)
Format name Header Station No. Command
Command type
Error code Tail BCC
Frame (Ex.) NAK
H0A r SB
Error code (2)
ETX BCC
ASCII value H15
H3041 H72 H5342
Error code (4)
H03
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