Err (error) will be displayed and it won't be possible to input the signal if you attempt to input a setting that was already set with another Multi-function Input selector.

For example, when a multi-step speed command is being used in a 3G3JV Inverter and you attempt to set n37 (Multi-function Input 2 selector) to 6 (multi-step speed command 1), Err (error) will be displayed and it won't be possible to input the signal.

This error occurred because n39 (Multi-function Input 4 selector) is set to its default setting of 6, and this setting was duplicated.
Set n37 (Multi-function Input 2 selector) to 6 after setting another value in n39 (Multi-function Input 4 selector).