Data Types and Registers
What you will find in this section:
Data types and registers
The Modbus specifications does not include requirements on how various data types are to be displayed on the respective register.
The specification only defines that the register has to be represented as “big endian”. This means that the high byte of a register is sent first, followed by the low byte.
8-bit integer types:
Example: Value = 1 (0x01)
|
Register address |
Register contents (hex) |
|
n |
0x0001 |
16-bit integer types:
Example: Value = 4660 (0x1234)
|
Register address |
Register contents (hex) |
|
n |
0x1234 |
32-bit integer types:
Example: Value = 305419896 (0x12345678)
|
Register address |
Register contents (hex) |
|
n |
0x5678 |
|
n +1 |
0x1234 |
32-bit IEE 754 floating point:
Example: Value = 123.456 (0x42F6E979)
|
Register address |
Register contents (hex) |
|
n |
0xE979 |
|
n +1 |
0x42F6 |
ASCII strings:
Example: Value = EEM-MA (0x45, 0x45, 0x4D, 0x2D, 0x4D, 0x41, 0x33, 0x37, 0x30 -> ASCII coded)
|
Register address |
Register contents (hex) |
|
n |
0x4545 |
|
n +1 |
0x2D4D |
|
n +2 |
0x414D |
|
n +3 |
0x3733 |
|
n +4 |
0x0030 |
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