#include <softwareserial.h>

#define SIM800_TX_PIN 2  //SIM800 TX is connected to Arduino D2

#define SIM800_RX_PIN 3 //SIM800 RX is connected to Arduino D3

//Create software serial object to communicate with SIM800
SoftwareSerial serialSIM800(SIM800_TX_PIN,SIM800_RX_PIN);

int PWX = 4;

void setup() {

  pinMode(PWX, OUTPUT);

  //Begin serial communication with Arduino and Arduino IDE (Serial Monitor)
  Serial.begin(9600);   //Begin serial communication with Arduino
  while(!Serial);       //Monitor Comms on Arduino IDE (Serial Monitor)

  //Being serial communication with Arduino and SIM800
  serialSIM800.begin(9600);
  delay(1000);

  Serial.println("Setup Complete!");

  digitalWrite(PWX, HIGH);
  delay(3000);
  digitalWrite(PWX, LOW);
  delay(1000);
  Serial.println("Start");
}

void loop() {
  //Read SIM800 output (if available) and print it in Arduino IDE Serial Monitor
  if(serialSIM800.available()){
    Serial.write(serialSIM800.read());
  }
  //Read Arduino IDE Serial Monitor inputs (if available) and send them to SIM800
  if(Serial.available()){
    serialSIM800.write(Serial.read());
  }
}