#define MAXBUFFER 20 // für längstes Kommando auf Serial In

// --------------- serial in ---------------
  if (Serial.available() > 0) {
    char incomingByte = (char)Serial.read();
    if(incomingByte == 13) { // Wenn das Enter ankommt
      strcpy(serial_in_command, serial_in_buff);
      memset(&serial_in_buff[0], 0, sizeof(serial_in_buff)); // 30.554 Bytes
      chr_cnt = 0;
    } // if(incomingByte == 13)
    else { // Falls kein Enter kommt muss der Text gespeichert werden in dem inText Array
      if(isprint(incomingByte)) {
        if(chr_cnt<(MAXBUFFER-2))
          serial_in_buff[chr_cnt++] = incomingByte;
        else {
          Serial.println(F("serBUF ov-> DEL"));
          memset(&serial_in_buff[0], 0, sizeof(serial_in_buff)); // 30.554 Bytes
          chr_cnt=0;
//          memset(&serial_in_command[0], 0, sizeof(serial_in_command)); // 30.554 Bytes
//          *serial_in_command=0;
        } // if(chr_cnt<(MAXBUFFER-1))
      } // if(isprint(incomingByte))
    } // if !(incomingByte == 13)
  } // if (Serial.available() > 0) 

  if(strlen(serial_in_command)) {
    Serial.println(); Serial.print(serial_in_command); Serial.println(F("->erkannt")); // 30.608 Bytes
    if( strstr(serial_in_command, "help") || ( strstr(serial_in_command, "?") && strlen(serial_in_command)==1 ) ) { // help screen
      Serial.println();
      Serial.println(F("commands:\n"));
      Serial.println(F("hellp, hellm, hellxx(0-10)"));
      Serial.println(F("conp, conm, conxx(55-75)"));
      Serial.println(F("date, dateJJJJ/MO/TA"));
      Serial.println(F("time, timeHH:MM:SS"));
      Serial.println(F("reset"));
      Serial.println(F(""));
      memset(&serial_in_command[0], 0, sizeof(serial_in_command)); // 30.554 Bytes
    } // if( strstr(serial_in_command, "help") || ( strstr(serial_in_command, "?") && strlen(serial_in_command)==1 ) )