FF
Unit ID
1 Byte, 0xFF = Master device
10
Function Code
1 Byte, 10 = Write
0130
Starting Address
2 Bytes, address of the first register
0001
Quantity of Registers
2 Bytes, the number of required registers
5.2.8. Read DI Status of Cascading Device (0x02)
Acquire 4-channel DI of cascaded device C2000-A2-SDD4040-AD1 with address 01 connected to the device
(C2000-A1-SDD1010-AB3), the command is as follows:
000100000006010200C80004
Command
Field
Description
0001
Transaction ID
2 Bytes, identification of a Modbus Request/Response transaction
0000
Protocol ID
2 Bytes, 0000 = Modbus protocol
0006
Length Field
2 Bytes, number of following bytes
01
Unit ID
1 Byte, 01 = RS485 address of the cascading device
02
Function Code
1 Byte, 02 = Read
00C8
Starting Address
2 Bytes, address of the first register
0004
Quantity of Registers
2 Bytes, the number of required registers
Assuming DI1-DI2 of the C2000-A2-SDD4040-AD1 is close, and DI3-DI4 of the C2000-A2-SDD4040-AD1 is open.
In the response from the device we get:
0x00010000000401020103
Command
Field
Description
0001
Transaction ID
2 Bytes, identification of a Modbus Request/Response transaction
0000
Protocol ID
2 Bytes, 0000 = Modbus protocol
0004
Length Field
2 Bytes, number of following bytes
01
Unit ID
1 Byte, 01 = RS485 address of the cascading device
02
Function Code
1 Byte, 02 = Read
01
Starting Address
2 Bytes, address of the first register
C2000-A1-SDD1010-AB3 User Manual
31 / 34
SinoCon Co., Ltd.
www.sinoconsys.com
