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Modbus tag name syntax
In the following table, the available syntaxes of the tag names are summarized.
| Operator | Function | Description |
| Rn:e | 16-bit signed integer stored in input register at address e | Read access only. Read function: 4 Standard address range: 30001-39999 |
| R:e | 16-bit unsigned integer stored in input register at address e | |
| H:e | 16-bit unsigned integer stored in holding register at address e | Read/write access. Read function: 3 Write function: 16 Standard address range: 40001 – 49999(extended to 499999 by some manufacturers) |
| Hn:e | 16-bit signed integer stored in holding register at address e | |
| Hf:e | Float number stored in holding register at address e | |
| Hfs:e | ||
| Hfsb:e | ||
| Hfsw:e | ||
| Rf:e | Float number stored in input register at address e | |
| Rfs:e | ||
| Rfsb:e | ||
| Rfsw:e | ||
| Hd:e | 32-bit integer stored in holding register at address e | |
| Hds:e | ||
| Hdsb:e | ||
| Hdsw:e | ||
| Rd:e | 32-bit integer stored in input register | |
| Rds:e | at address e | |
| Rdsb:e | ||
| Rdsw:e | ||
| I:e | Discrete input, Boolean value | Read access only. Read function: 2 Standard address range: 10000-19999 |
| O:e | Discrete Output Coils | Read/write access: Read function: 1 Write function: 15 Standard address range: 1-9999 |
Many manufacturers use addresses instead of tags when describing Modbus communication. mySCADA currently does not support direct access by address, so you have to convert such addresses to tags, according to the provided table above. Be aware that specific read/write functions are needed to access each range, so the correct choice of tag type is important.