ICP DAS USA tWF-DA1PD2R1 User Manual page 29

describe the different byte of encoding and show how the data is encoded as it is within
the Modbus/TCP packet.
5.2.5.1 Binary
A binary item is represented as a single bit within a data word. All binary is packed
into 16-bits data words, which are accessed using function code 01 and 02. Therefore, a
single register contains 16 bits of binary data, each having a specific meaning.
(1010101001010101)
Table 5-3: A single register contains 16 bits of binary data
5.2.5.2 16-bits Word
A 16-bits word item is transmitted with the most significant byte first. Function code
03 and 04 read 16-bits items at a time; therefore, each of these data items will fit within
one register that is read.
5.2.5.3 32-bits Double Word
A 32-bits word item is transmitted with the most significant byte first. Function 04
read 32-bits items at a time; therefore, each of these data items will fit within 2 register
that is read.
0x12345678
tWF-DA1PD2R1
tWF-DA1PD2R1 User's Manual
Value
0xAA55
Value
0x1234
Table 5-4: A 16-bits word item
Value
Table 5-5: A 32-bits double word item
User's Manual (Rev1.0, APR./2019) ------------- 29
1st
0xAA
(10101010)
1st
0x12
st
1 Word
0x5678
2nd
0x55
(01010101)
2nd
0x34
nd
2 Word
0x1234