Nor-Cal SDC15 Controller User Manual
Page 182
• Example in case of error
(1) Start of message
(2) Station address
(3) Error flag (since undefined "04" is sent as a command with a send message, the most
significant bit is turned ON and sent back as "84".)
(4) Abnormal termination code (
(5) Checksum (LRC)
(6) Delimiter
MODBUS RTU
• Example in case of normal reception
(1) Station address
(2) Read command
(3) Read count X 2 (bytes)
(4) Read data 1
(5) Read data 2
(6) Checksum (CRC)
• Example in case of error
(1) Station address
(2) Error flag (since undefined "04H" is sent as a command with a send message, the most
significant bit is turned ON and sent back as "84H".)
(3) Abnormal termination code (
(4) Checksum (CRC)
8-8
Chapter 8. MODBUS COMMUNICATIONS FUNCTIONS
(2)
(1)
(3)
(4)
3AH
:
30H
0
41H
A
38H
8
34H
4
30H
0
31H
1
(5)
(6)
37H
7
31H
1
0DH
CR
0AH
LF
(2)
(1)
(3)
(4)
0AH 03H 04H 03H 01H 00H 03H
(5)
(6)
51H 76H
(2)
(1)
(3)
0AH 84H 01H F3H 02H
(4)