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4.3. Data Encoding
Modbus uses a “big
-
endian” representation for address and data items. This means
that when a numerical quantity larger than single byte is transmitted, the most
significant byte (MSB, also called the high-order byte) is send first. The following
sub-topics describe the different byte of encoding and show how the data is
encoded as it is within the Modbus/TCP packet.
4.3.1. 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.
Value
1st
2nd
0xAA55
(1010101001010101)
0xAA
(10101010)
0x55
(01010101)
4.3.2. 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.
Value
1st
2nd
0x1234
0x12
0x34
Summary of Contents for OME-ET-7000 Series
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Page 37: ...Page 32 The lower section of the page provides a brief introduction to the web interface...
Page 86: ...Page 81 After completing the configuration click the Submit button to save the settings 1 2...
Page 92: ...Page 87 The default URL that the More Information item will link to http www omega com...
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