Modbus Mapping
What you will find in this section:
Modbus mapping
The EMpro offers the option of mapping various registers to a defined contiguous Modbus register area.
This allows multiple registers from different address spaces to be retrieved in a single read command.
- The contiguous area comprises 125 registers, as this is the maximum number of registers that can be read in one read command
- The mapping is limited to process data, as this is considered relevant for this application
- The mapping is implemented at register level, independent of data points and data types.
The 125 mapped register addresses - starting at register 57.600 (Hex: 0xE100) – can only be read by the user.
The assignment of content for these registers takes place in the 125 registers starting at 57.344 (Hex: 0xE000) and is also possible via the web server. Configuration via the display is not provided.
Example:
The system conductor voltage (register: 32829), the system current (register: 32825), the frequency (register 32.780) and the total active power (register 32.790) are to be received via a read command.
- For this it is necessary to store the registers to be mapped in the allocation registers. The number of registers to transfer a value depends on the data type. All register addresses must be stored in the allocation registers.
57.344: 32.829
57.345: 32.830
57.346: 32.825
57.347: 32.826
57.348: 32.780
57.349: 32.781
57.350: 32.790
57.351: 32.791
57.352: 16.452
- The format of query must then be set according to the configured input data in the mapped register addresses.
57.600 → 32 Bit Float (little endian byte swap)
57.602 → 32 Bit Float (little endian byte swap)
57.604 → 32 Bit Float (little endian byte swap)
57.606 → 32 Bit Float (little endian byte swap)
57.608 → 16 Bit Integer (little endian byte swap)
