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7.2
Modbus function code 0x03 Demonstration
I.
Use Modbus RTU/ASCII to read single-chip counter module registers
Modbus function code
Transmission example
(ID:0x01)
Respond example (ID:0x01)
0x03
01 03 10 00 00 02
01 03 04 00 00 00 00
※
In this example, we are reading “0x1000 and 0x1001 channel 1” with the I/O
module ID of “01”
※
When not using control modules for communications, the addresses for the
registers will be:0x1000 (CH0 high-order word), 0x1001 (CH0 low-order word),
0x1002 (CH1 high-order word), 0x1003 (CH1 low-order word), 0x1004 (CH2 high-
order word), 0x1005 (CH2 low-order word), 0x1006 (CH3 high-order word) and
0x1007 (CH3 low-order word).
II.
Use Modbus RTU/ASCII with control modules to read analog input registers
Modbus function code
Transmission example
(ID:0x01)
Respond example (ID:0x01)
0x03
01 03 10 00 00 02
01 03 04 00 00 00 00
※
In this example, we are reading “0x1000 and 0x1001 channel 1” with the control
module ID of “01”
※
When using control modules for communications, the addresses for the registers
will start at: 0x1000 (CH0 high-order word), 0x1001 (CH0 low-order word), 0x1002
(CH1 high-order word), 0x1003 (CH1 low-order word), 0x1004 (CH2 high-order
word), 0x1005 (CH2 low-order word), 0x1006 (CH3 high-order word) and 0x1007
(CH3 low-order word).
