   T1        get Temperature T1, returns deg C as string
   T2        get Temperature T2, returns dec C as string
   VERSION   get firmware version string
-  X         shutdown, set LED1, Q1, Q2 to zero
+  X         shutdown, set Q1, Q2 to zero
 
   LED1 is on during normal operation.
 

  
  // separate command from associated data
  int idx = read_.indexOf(sp);
  String cmd = read_.substring(0,idx);
  cmd.trim();
  cmd.toUpperCase();

  // extract data. toInt() returns 0 on error
  String data = read_.substring(idx+1);
  data.trim();
  int pv = data.toInt();
  
  // process commands
  if (cmd == "LED1") {
    analogWrite(pinLED1, max(0,min(limLED1,pv)));
  }
  else if (cmd == "Q") {
    analogWrite(pinQ1, max(0,min(limQ1,pv)));
    analogWrite(pinQ2, 0);
  }

  }
}


// check alarms and update status on LED1
void AlarmsCheck(void) {
  if ((analogRead(pinT1) > limT1) or (analogRead(pinT2) > limT2)) {
    analogWrite(pinLED1,limLED1);
  } else {
