Implementing Modbus TCP
Almost all implementations have variations from the official standard. Different varieties may not communicate correctly between different suppliers equipment. Some of the most common variations are:
Data Types
- Floating Point IEEE
- 32 bit integer
- 8 bit data
- mixed data types
- bit fields in integers
- multipliers to change data to/from integer. 10, 100, 1000, 256 …
Protocol extensions
- 16 bit slave addresses
- 32 bit data size (1 address = 32 bits of data returned.)
- word swapped data