# Changing the ID of a Modbus RTU slave

Each slave is identified by a slave ID which is unique in the scope of the master. In the device tree, slaves are sorted by their slave IDs .

1. Open the device view.
2. In the device tree, double-click the slave you want to delete a data item from.
3. In the combo box Slave ID, enter a unique slave ID in the range of 1 to 247.
4. Press Enter.

5. ## NOTICE

   If you entered an invalid slave ID (e. g. the number is out of range), the slave ID will be automatically reset to the last valid slave ID.