Send Serial Data From Arduino Mega To Uno Using ARC

Hello I can't wrap my head around how to send serial data from a Arduino Mega to a Arduino Uno USING ARC (2020-04-10)

Installing EZ-Mega-v1-636848729355769322.zip on the Mega and using ARC to talk to it works fine. (only done basic servo and LED control) The Uno has just a standard Arduino sketch (See below for code)

The mega pins using 18-TX1 & 19-RX1 to Uno 0-RX & 1-TX with GND on both boards connected to each other. I thought using

SendSerial(d18, 9600, "1")  - via ARC script, or "1" in the serial terminal

would send a 1 from the Mega to the Uno, to turn LED on/off When sending command, the Mega (TX & RX flashes) Uno (RX flashes). What else in ARC do I need to setup for this to work.?

Any help appreciated. 

NEW CODE ON UNO

int led = 13; void setup() { pinMode(13,OUTPUT); Serial.begin(9600); Serial.flush(); } void loop() { while (Serial.available() >0) { int input = Serial.read(); if (input == 1) digitalWrite(led, HIGH); else if (input == 2) digitalWrite(led, LOW);
} }

Using Mega as master and uno as slave (plain arduino setup) this code works fine via Arduino serial monitor.

Arduino MEGA (MASTER)

void setup() {
Serial.begin(9600); Serial1.begin(9600); }

void loop() { String readString; String Q; while (Serial1.available()){ delay(1); if(Serial1.available()>0){ char c = Serial1.read(); Serial.print(c); if (isControl(c)){ break; }
} } while (Serial.available()) { delay(1); if (Serial.available() >0) { char c = Serial.read(); if (isControl(c)) { break; } readString += c;
} }

Q = readString; if(Q=="1"){
Serial1.print("1"); Serial.println("Sent:On");
} if(Q=="2"){
Serial1.print("2");
Serial.println("Sent:Off");
} }

Arduino UNO (Slave)

• • • • • • • • • • • • • *  void setup() { pinMode(13,OUTPUT); Serial.begin(9600); }

void loop() { String readString; String Q;

while (Serial.available()) { delay(1); if (Serial.available() >0) { char c = Serial.read(); //gets one byte from serial buffer if (isControl(c)) { //'Serial.println("it's a control character"); break; } readString += c; //makes the string readString
} }

Q = readString; //--------Checking Serial Read---------- if(Q=="1"){
digitalWrite(13,HIGH);
} if(Q=="2"){
digitalWrite(13,LOW);
} }

Thanks Steve