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5 Serial Gateway
5-34
CJ-series Serial Communications Units Operation Manual for NJ-series CPU Unit(W494)
z
Response Frame
z
Command Frame
Note The silent interval in the Modbus-RTU frame is automatically generated by the Serial Communi-
cations Unit.
5-6-2 Modbus-RTU
Frame before Conversion
CompoWay/F
(See note.)
Command
end code
Command Header
Frame after Conversion
CompoWay/F
STX
(02 hex) Node No.
(
×
10
1
)
(
×
10
2
)
(ASCII
code
2 bytes)
Remote
network
address
(DNA) Remote
node
address
(DA1) SRC MRC MRES SRES
Serial
port
allocated
address 00 hex Serial
port unit
address
03
28
Node No.
(
×
10
1
)
(
×
10
2
)
(ASCII code
2 bytes)
Sub-
address
"00"
(ASCII code
3030 hex)
etc. Command
(MRC,
SRC)
(ASCII
code
4 bytes) End code
(ASCII
code
2 bytes) Response
(MRES,
SRES)
(ASCII
code
4 bytes) Text
(ASCII
code)
Sub-
address
"00"
(ASCII
code 3030
hex) etc. Command
(MRC,
SRC)
(ASCII
code
4 bytes) Text
(ASCII
code) Response
(MRES,
SRES)
(ASCII
code
4 bytes) ETX
(03 hex) BCC End code
(ASCII
code
2 bytes)
Remote
unit
address
(DA2) etc.
User-
speci-
fied User-
speci-
fied
Frame before Conversion
Header
Frame after Conversion
Command
Remote
network
address
(DNA) Remote
node
address
(DA1) Remote
unit
address
(DA2) Etc. MRC SRC
Serial port
allocated
address 00 hex Serial
port
unit
address 28 04
or local
network
address or local
network
node
address
Modbus-RTU frame
Start (silent
interval of
3.5
characters)
(See note.) Slave
address
(1 byte) FUNCTION
code
(1 byte) Communications data
(n bytes) Error
check
CRC
(1 byte) End (silent
interval of
3.5
characters)
(See note.)
Modbus-RTU
(command section only)
Slave
address
(1 byte) FUNCTION
code(1 byte) Communications data
(n bytes)