# Editing a configuration file

1. Open the configuration file.
2. In the square brackets, enter the Modbus TCP register address, the global variable and the Modbus TCP datatype as shown in the example below.

4. ## ATTENTION

   Each variable is mapped to one Modbus register (16 bit) only. If, e. g., a 32-bit variable is mapped to a Modbus register, the upper 16 bits will be truncated.

5. ## NOTICE

   Use input_register to read the value of a global variable from the real-time application. Use holding_register to write to a global variable in the real-time application. If you use holding_register for reading, the value of the global variable in the real-time application will be overwritten by the Modbus TCP slave.

6. ## NOTICE

   If you rename a global variable in your project, you must change the name of the variable in the configuration file accordingly.

7. Change the update interval to the desired value (µs).

Load the configuration file.

Loading a configuration file