Datasheet

Once done it will automatically reply, which is a way for the radios to know that there was an acknowledgement

It simply sends back a string and waits till the reply is completely sent

// Send a reply

uint8_t data[] = "And hello back to you";

rf95.send(data, sizeof(data));

rf95.waitPacketSent();

Serial.println("Sent a reply");

https://learn.adafruit.com/adafruit-rfm69hcw-and-rfm96-rfm95-rfm98-lora-packet-padio-

breakouts

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