Modbus-Ascii - Omron CJ - REFERENCE MANUAL 07-2009 Reference Manual

Communications Frames
Response Frame
3-7-3

Modbus-ASCII

Command Frame
Frame before Conversion
FINS header
Remote Remote
network node
address address
(DNA) (DA1)
Serial port 00 hex
allocated
address
or local or local
network network
address node
address
Frame after Conversion
Header
":"
(ASCII code
3A hex)
88
Frame before Conversion
Start (silent Slave
interval of
address
3.5
(1 byte)
characters)
(See note.)
Frame after Conversion
FINS header
Remote Remote
network node
address address
(DNA) (DA1)
Serial port 00 hex Serial
allocated
address
or local or local
network network
address node
address
FINS command
Remote Etc. MRC SRC
unit
address
(DA2)
Serial
28 05
port
unit
address
Modbus-ASCII frame
Slave address FUNCTION code
(ASCII code (ASCII code
2 characters: 2 characters:
4 bytes) 4 bytes)
Modbus-RTU frame
FUNCTION Communications data
code (n bytes)
(1 byte)
FINS command FINS end code
Remote Etc. MRC SRC MRES
unit
address
(DA2)
28 04 User-
port speci-
unit fied
address
Modbus-ASCII
(command section only)
Slave FUNCTION
address code
(ASCII code (ASCII code
2 characters: 2 characters:
4 bytes) 4 bytes)
Communications data CR
(ASCII code n characters) (0D hex)
Section 3-7
Error End (silent
interval of
check
3.5
CRC
characters)
(1 byte)
(See note.)
SRES
Modbus-RTU
(command section only)
User- Slave FUNCTION
speci- address code (1 byte)
fied (1 byte)
Communications data
(ASCII code n characters)
LF
(0A hex)
Communica-
tions data
(n bytes)