Flysky and Relay

Projects General Guidance
19

forward and plow are variables you never set. They are initialised to 0. You are misusing them, it is no surprise you get "nothing".

You need to learn more about variables, digitalRead and digitalWrite.

Meanwhile try this loop(), adjust the constants using what you learned by printing the values that your pulseIn calls showed you when you printed them.

I assume you have LEDs that are working on your output pins. You could write a small bit of code to test that... just sayin'.

void loop()
{
  sig1 = pulseIn(ch1, HIGH);
  sig6 = pulseIn(ch6, HIGH);

   if(sig1 > 1900)
   {
     digitalWrite(sd1, HIGH);
   }
   
   if(sig1 < 1000)
   {
     digitalWrite(sd1, LOW);
   }

    if(sig6 > 1900)
   {
     digitalWrite(sd6, HIGH);
   }
   
   if(sig6 < 1000)
   {
     digitalWrite(sd6, LOW);
   }
       
   delay(200);
}

HTH

a7