How to communicate in XCTU

Hello there,
I have 3 XBee pro running. One is connected to the XCTU app (screen):

I would like to send some data from NODE1 to NODE2 and NODE3. If I understand correctly, in the terminal view I can send/ receive data from the module I am currently connected to through uart (NODE1)? What would be the command, for instance, to read NI from NODE2 through connected NODE1? I would appreciate all help.

That requires API mode and the use of the Remote AT command function. That is the 0x17 API frame.

Thank you for answer, that was indeed the case. Should all nodes be set to api mode in a DigiMesh network? Assuiming every node is a device, that can do something (read sensor data, etc).

API mode is only needed on that module if the device it is connected to can communicate using the API frames. Otherwise it should be in transparent mode. And before you ask, yes, you can mix modules on the same network with some using API and others in transparent.

To have clarity: is an API frame any communicate, that is send to the module using UART/SPI? In other words, If an mcu is connected to the module using uart, should the module be configured in API mode?

If you are using the UART, regardless if it is a uP or not that is connected, you can use either API or the default transparent mode. API mode is ONLY required for the SPI interface.

So that means only AT commands configure the local Xbee module?

If you are in transparent mode, that is correct. Only AT commands and AT command mode can modify the radios settings via the UART.