Omron CS CJ1W-ETN21, Quick Start Manual, Page: 9 / 14

MANUEL STA46 Modbus TCP
JP Viskovic 30/08/2005 OEE-F 9
1-4-3 I/O memory area (CIO) Read Multiple Registers
[Function]
Reads registers in I/O memory area
[Request]
Length Data
Function Code 1 Byte 0x04
Starting Address 2 Bytes 0x0000-0x16A8
Quantity of Registers 2 Bytes 1-125(0x7D)
[Response]
Length Data
Function Code 1 Byte 0x04
Byte Count 1 Byte N x 2(*)
Register Value N x 2 Bytes
(*)N=Quantity of Registers
Example: read 3 words (CIO 1000 to CIO 1002)
Request Response
Data Data
Function Code 0x04 Function Code 0x04
Starting Address(H) 0x03 Byte Count 0x06
Starting Address(L) 0xE8 Register Value(H)CIO1000 0xAB
Quantity of Registers(H) 0x00 Register Value(L)CIO1000 0x12
Quantity of Registers(L) 0x03 Register Value(H)CIO1001 0x56
Register Value(L)CIO1001 0x78
Register Value(H)CIO1002 0x97
Register Value(L)CIO1002 0x13
DM 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1000
A B 1 2
1001 5 6 7 8
1002 9 7 1 3