APC 220 - Configuration

I’m trying to connect a pair of APC 220; one is connected to a drone, the other one to my laptop which runs Linux.

I uploaded the following code on both APC to run some experiments :

#include <SoftwareSerial.h>

const int PIN_APC_RX  = 11;
const int PIN_APC_TX  = 12;
const int PIN_APC_SET = 13;

SoftwareSerial APC(PIN_APC_RX, PIN_APC_TX);

void setup() {
    Serial.begin(9600);
    
    pinMode(PIN_APC_SET, HIGH);
    APC.begin(9600);

    digitalWrite(PIN_APC_SET, LOW);
    delay(10);

    APC.println("WR 433900 3 9 3 0");
    delay(10);

    digitalWrite(PIN_APC_SET, HIGH);
    delay(200);
}
void send_APC() {
    char rc;
    while (Serial.available() > 0) {
        rc = Serial.read();
        APC.write(rc);
    }
}
void read_APC() {
     while (APC.available() > 0) {
        rc = APC.read();
       Serial.print(rc);
    }
}

:frowning: I am not able to transmit/receive data on any device. Has anyone ever solved that before ?

Always post the complete, compilable code.