Data Coercion
About this task
The Modbus RTU Slave Interface performs runtime coercion for all data types.
Discrete data types are coerced according to the following guidelines.
| Memory Type | Data Source | Source Value | Target Value |
| 0X | CIMPLICITY | zero (0) | 0 |
| CIMPLICITY | non-zero (!= 0) | ||
| Modbus master | 0 | ||
| Modbus master | 0xFF or 0x01 (depends on function code) | ||
| 1X | CIMPLICITY | zero (0) | 0 |
| CIMPLICITY | non-zero (!= 0) |
guide: Guidelines. Analog data types are coerced according to the following guidelines.
Procedure
- For analog points with engineering units, the Modbus RTU Slave Interface will use the engineering unit value when converting to/from Modbus data values.
- For analog points without engineering units, the Modbus RTU Slave Interface will transfer the raw value.
- CIMPLICITY point values will be coerced to two byte unsigned integer values. Thus, the fractional portion of real values will be lost.
- The Modbus RTU Slave Interface will reject any CIMPLICITY point value outside of the range defined by the Modbus Register Limits. .