Firmata.SendString не работает с конкретными переменными `char`

У меня есть скетч Firmata, который принимает строковые сообщения, разделяет их и отправляет свои части обратно в клиентскую программу Firmata. Моя проблема, безусловно, на стороне автора. Проблема в том, что методы Firmata.sendString(аргумент1) и Firmata.sendString(аргумент2) ничего не отправляют. Более подробная информация содержится в коде скетча. Как я могу заставить методы sendString работать?

/*
 * This sketch accepts strings in the following form:
 * CMDn(arg1,arg2)
 * CMDn — command name,
 * arg1 и arg2 — unnecessary arguments.
 * Each argument's length can be from 1 to 4 characters,
 * They're saved to separate variables.
 *
 * This sketch sends back the parsed commands partially:
 * the command name, argument #1 (if present), argument #2 (if present)
 */


#include <Firmata.h>


void stringCallback(char *received) {
  //CMDn(arg1,arg2)
  //CMDn(arg1)
  //CMDn(1)
  //CMDn()
  //012345678901234
  //          11111

  //This scheme up there is just for 
  //understanding the indexes of the chars in the string
  //in its various possible variations

  //Let's declare all the necessary variables
  char methodName[5];
  char argument1[5];
  char argument2[5];
  byte commaLocation = 0;

  //If the received string doesn't match the strings' syntax,
  //send an error message
  if (!(received[4] == '(' && strlen(received) <= 15)) {
    Firmata.sendString("ERR;");
    return;
  }

  //Let's take the 0-3 chars in the string and send it back.
  //It's probably the command name
  for (int i = 0; i < 4; i++) {
    methodName[i] = received[i];
  }
  methodName[4] = '\0'; //does or doesn't the compiler add the terminator automatically?
  Firmata.sendString(methodName); //send it
  //This string is being sent without problems.


  //If there is some arguments in the string,
  //it is detectable if the string char 5 is not ')'/
  if (received[5] != ')') {
    //Lent's find out if the input string has a `comma`
    //inside the parentheses. If it does, it means that
    //there are two arguments in the string.

    Firmata.sendString("46 passed");    
    for (int i = 6; i < (strlen(received) - 1); i++) {
      //If there is a comma, save its' index and break the loop
      if (received[i] == ',') {
        commaLocation = i;
        break;
      }
    }

    //If a comma is not present, its location variable equals 0,
    //sincerely we just collect all the chars between the parentheses
    //to the 'argument1' variable and send it.
    if (commaLocation == 0) {
      Firmata.sendString("61 passed");
      for (int i = 5; i < ; i++) {
        argument1[(i - 5)] = received[i];
      }


      argument1[strlen(argument1)] = '\0'; //Either this is executed or not, the outcome doesn't change 

      Firmata.sendString(argument1); //This very command doesn't work. It just does not send anything. 
                                     //Looks like 'argument1' is empty, but I'm awfully sure that it must 
                                     //not be empty. Anyway, the 'argument1' does not show up in the client
    }

    //If there is a comma present, then write chars before the comma
    //to 'argument1', and after the comma - to 'argument2'
    if (commaLocation != 0) {
      Firmata.sendString("77 passed");
      //let's write what is before the comma:
      for (int i = 5; i < commaLocation; i++) {
        argument1[i - 5] = received[i];
        Firmata.sendString("81 iterator");
      }

      //let's write what's after the comma;
      char argument2[5];
      for (int i = (commaLocation + 1); i < (strlen(received)); i++) {
        argument2[(i - (commaLocation + 1))] = received[i];
        Firmata.sendString("87 iterator");
      }
      
      argument1[strlen(argument1)] = '\0'; //Either this is executed or not, the outcome doesn't change 
      argument2[strlen(argument2)] = '\0'; 

      Firmata.sendString(argument1); //Not working
      Firmata.sendString(argument2); //Not working
    }
  }
}


void sysexCallback(byte command, byte argc, byte *argv) {
  Firmata.sendSysex(command, argc, argv);
}


void setup() {
  Firmata.setFirmwareVersion(FIRMATA_FIRMWARE_MAJOR_VERSION, FIRMATA_FIRMWARE_MINOR_VERSION);
  Firmata.attach(STRING_DATA, stringCallback);
  Firmata.attach(START_SYSEX, sysexCallback);
  Firmata.begin(57600);
}

void loop() {
  while (Firmata.available()) {
    Firmata.processInput();
  }
}

Ожидаемый результат:

Реальный результат: