I think I need to send command RD to APC220. How to do this?
In what way does this question relate to Arduino?
pylon:
In what way does this question relate to Arduino?
APC220 is connected to Arduino Uno. Need to check module configuration.
26iyo:
https://image.dfrobot.com/image/data/TEL0005/APC220_Datasheet.pdfI think I need to send command RD to APC220. How to do this?
simply use serial.println("RD") to send the command! 
there is an example script here:
hope that helps...
sherzaad:
simply use serial.println("RD") to send the command!there is an example script here:
Configuring an APC220 RF transceiver with Arduino | Allodoxaphobiahope that helps...
Is it possible to use this command with Linux OS? I don't want to mess my Arduino setup.
I just need to know what frequency is used.
The APC220 has its own microprocessor and as explained in the data sheet, speaks serial ASCII.
Just use a terminal program, a USB-TTL serial port adapter and configure the APC220 directly using ANY type of computer.