diff --git a/drv/b15f.cpp b/drv/b15f.cpp
index c58b4eb..edc8c1c 100644
--- a/drv/b15f.cpp
+++ b/drv/b15f.cpp
@@ -11,24 +11,7 @@ void B15F::init()
 {
 	
 	std::cout << PRE << "Stelle Verbindung mit Adapter her... " << std::flush;
-	int code = system(std::string("stty " + std::to_string(BAUDRATE) + " -F " + SERIAL_DEVICE).c_str());
-	if(code)
-	{
-		throw DriverException("Konnte serielle Verbindung nicht initialisieren. Ist der Adapter angeschlossen?");
-	}
-	
-	usart = open(SERIAL_DEVICE.c_str(), O_RDWR | O_NOCTTY | O_NDELAY);
-	struct termios options;
-	tcgetattr(usart, &options);
-	options.c_cflag = CS8 | CLOCAL | CREAD; 
-	options.c_iflag = IGNPAR;
-	options.c_oflag = 0;
-	options.c_lflag = 0;
-	options.c_cc[VTIME]=100; // timeout in Dezisekunden
-    cfsetspeed(&options, BAUDRATE);	
-	tcsetattr(usart, TCSANOW, &options);
-	tcflush(usart, TCIOFLUSH); // leere Puffer in beiden Richtungen
-	
+	usart.openDevice(SERIAL_DEVICE);	
 	std::cout << "OK" << std::endl;
 	
 	delay_ms(1);
@@ -82,13 +65,13 @@ void B15F::reconnect()
 
 void B15F::discard(void)
 {
-	tcflush(usart, TCOFLUSH); // leere Ausgangspuffer
+	usart.clearOutputBuffer();
 	for(uint8_t i = 0; i < 8; i++)
 	{
-		writeByte(RQ_DISC);	// sende discard Befehl (verwerfe input)
+		usart.writeByte(RQ_DISC);	// sende discard Befehl (verwerfe input)
 		delay_ms((16000 / BAUDRATE) + 1); // warte mindestens eine Millisekunde, gegebenenfalls mehr
 	}
-	tcflush(usart, TCIFLUSH); // leere Eingangspuffer
+	usart.clearInputBuffer();
 }
 
 bool B15F::testConnection()
@@ -97,11 +80,11 @@ bool B15F::testConnection()
 	srand(time(NULL));
 	uint8_t dummy = rand() % 256;
 	
-	writeByte(RQ_TEST);
-	writeByte(dummy);
+	usart.writeByte(RQ_TEST);
+	usart.writeByte(dummy);
 	
-	uint8_t aw = readByte();
-	uint8_t mirror = readByte();
+	uint8_t aw = usart.readByte();
+	uint8_t mirror = usart.readByte();
 	
 	return aw == MSG_OK && mirror == dummy;
 }
@@ -111,10 +94,10 @@ bool B15F::testIntConv()
 	srand(time(NULL));
 	uint16_t dummy = rand() % (0xFFFF / 3);
 	
-	writeByte(RQ_INT);
-	writeInt(dummy);
+	usart.writeByte(RQ_INT);
+	usart.writeInt(dummy);
 	
-	uint16_t aw = readInt();
+	uint16_t aw = usart.readInt();
 	return aw == dummy * 3;
 }
 
@@ -125,20 +108,20 @@ std::vector<std::string> B15F::getBoardInfo(void)
 	{
 		std::vector<std::string> info;
 		
-		writeByte(RQ_INFO);
-		uint8_t n = readByte();
+		usart.writeByte(RQ_INFO);
+		uint8_t n = usart.readByte();
 		while(n--)
 		{
-			uint8_t len = readByte();			
+			uint8_t len = usart.readByte();			
 			std::string str;
 			
 			while(len--)
-				str += static_cast<char>(readByte());
+				str += static_cast<char>(usart.readByte());
 				
 			info.push_back(str);
 		}
 		
-		uint8_t aw = readByte();
+		uint8_t aw = usart.readByte();
 		
 		if(aw != MSG_OK)
 			throw DriverException("Board Info fehlerhalft");
@@ -156,10 +139,10 @@ bool B15F::digitalWrite0(uint8_t port)
 {
 	try
 	{
-		writeByte(RQ_BA0);
-		writeByte(port);
+		usart.writeByte(RQ_BA0);
+		usart.writeByte(port);
 		
-		uint8_t aw = readByte();	
+		uint8_t aw = usart.readByte();	
 		return aw == MSG_OK;
 	}
 	catch(DriverException& de)
@@ -173,10 +156,10 @@ bool B15F::digitalWrite1(uint8_t port)
 {
 	try
 	{
-		writeByte(RQ_BA1);
-		writeByte(port);
+		usart.writeByte(RQ_BA1);
+		usart.writeByte(port);
 		
-		uint8_t aw = readByte();	
+		uint8_t aw = usart.readByte();	
 		return aw == MSG_OK;
 	}
 	catch(DriverException& de)
@@ -190,8 +173,8 @@ uint8_t B15F::digitalRead0()
 {
 	try
 	{
-		writeByte(RQ_BE0);
-		return readByte();
+		usart.writeByte(RQ_BE0);
+		return usart.readByte();
 	}
 	catch(DriverException& de)
 	{
@@ -204,8 +187,8 @@ uint8_t B15F::digitalRead1()
 {
 	try
 	{
-		writeByte(RQ_BE1);
-		return readByte();
+		usart.writeByte(RQ_BE1);
+		return usart.readByte();
 	}
 	catch(DriverException& de)
 	{
@@ -218,12 +201,12 @@ bool B15F::analogWrite0(uint16_t value)
 {
 	try
 	{
-		writeByte(RQ_AA0);
+		usart.writeByte(RQ_AA0);
 		delay_ms(1);
-		writeInt(value);
+		usart.writeInt(value);
 		delay_ms(1);
 		
-		uint8_t aw = readByte();	
+		uint8_t aw = usart.readByte();	
 		return aw == MSG_OK;
 	}
 	catch(DriverException& de)
@@ -237,10 +220,10 @@ bool B15F::analogWrite1(uint16_t value)
 {
 	try
 	{
-		writeByte(RQ_AA1);
-		writeInt(value);
+		usart.writeByte(RQ_AA1);
+		usart.writeInt(value);
 		
-		uint8_t aw = readByte();	
+		uint8_t aw = usart.readByte();	
 		return aw == MSG_OK;
 	}
 	catch(DriverException& de)
@@ -254,10 +237,10 @@ uint16_t B15F::analogRead(uint8_t channel)
 {
 	try
 	{
-		writeByte(RQ_ADC);
+		usart.writeByte(RQ_ADC);
 		delay_ms(1);
-		writeByte(channel);
-		return readInt();
+		usart.writeByte(channel);
+		return usart.readInt();
 	}
 	catch(DriverException& de)
 	{
@@ -273,13 +256,13 @@ bool B15F::analogSequence(uint8_t channel_a, uint16_t* buffer_a, uint32_t offset
 	
 	try
 	{
-		writeByte(RQ_ADC_DAC_STROKE);
-		writeByte(channel_a);
-		writeByte(channel_b);
-		writeInt(start);
-		writeInt(static_cast<uint16_t>(delta));
-		writeInt(count);
-		uint8_t aw = readByte();
+		usart.writeByte(RQ_ADC_DAC_STROKE);
+		usart.writeByte(channel_a);
+		usart.writeByte(channel_b);
+		usart.writeInt(start);
+		usart.writeInt(static_cast<uint16_t>(delta));
+		usart.writeInt(count);
+		uint8_t aw = usart.readByte();
 		
 		if(aw != MSG_OK)
 		{
@@ -290,7 +273,7 @@ bool B15F::analogSequence(uint8_t channel_a, uint16_t* buffer_a, uint32_t offset
 		uint8_t block[5]; // 4 Datenbyte + crc	
 		for(uint16_t i = 0; i < count; i++)
 		{
-			bool crc_ok = readBlock(&block[0], 0);
+			bool crc_ok = usart.readBlock(&block[0], 0);
 			
 			if (!crc_ok)
 			{
@@ -303,7 +286,7 @@ bool B15F::analogSequence(uint8_t channel_a, uint16_t* buffer_a, uint32_t offset
 			buffer_b[offset_b + i] = ((uint16_t) block[2]) | (((uint16_t) block[3]) << 8);
 		}
 		
-		aw = readByte();		
+		aw = usart.readByte();		
 		if(aw == MSG_OK)
 			return aw;
 		
@@ -317,126 +300,6 @@ bool B15F::analogSequence(uint8_t channel_a, uint16_t* buffer_a, uint32_t offset
 	}
 }
 
-
-void B15F::writeByte(uint8_t b)
-{	
-	if(write(usart, &b, 1) != 1)
-		throw DriverException("Fehler beim Senden. (byte)");
-}
-
-void B15F::writeInt(uint16_t v)
-{		
-	if(write(usart, reinterpret_cast<char*>(&v), 2) != 2)
-		throw DriverException("Fehler beim Senden. (int)");
-}
-
-uint8_t B15F::readByte()
-{
-	char b;
-	auto start = std::chrono::steady_clock::now();
-	auto end = start;
-	uint16_t elapsed = 0;
-	while(elapsed < timeout)
-	{
-		int n_ready;
-		int code = ioctl(usart, FIONREAD, &n_ready);
-		if(code != 0)
-				std::cout << PRE << "n_ready code: " << code << std::endl;
-		
-		if(n_ready > 0)
-		{				
-			//std::cout << code << " \tready: " << n_ready << std::endl;
-			
-			code = read(usart, &b, 1);
-			if (code > 0)
-				return static_cast<uint8_t>(b);
-			if (code < 0)
-				std::cout << PRE << "usart code: " << code << std::endl;
-		}
-		
-		end = std::chrono::steady_clock::now();
-		elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
-	}
-	
-	if(elapsed >= timeout)
-		throw DriverException("Verbindung unterbrochen. (timeout)");
-}
-
-uint16_t B15F::readInt()
-{
-	return readByte() | readByte() << 8;
-}
-
-bool B15F::readBlock(uint8_t* buffer, uint16_t offset)
-{
-	uint8_t len = readByte();
-	uint8_t crc = 0;
-	buffer += offset;
-	
-	// wait for block
-	int n_ready;
-	uint16_t elapsed = 0;
-	auto start = std::chrono::steady_clock::now();
-	auto end = start;
-	while(elapsed < block_timeout)
-	{
-		int code = ioctl(usart, FIONREAD, &n_ready);
-		if(code != 0)
-		{
-			std::cout << PRE << "n_ready code: " << code << std::endl;
-			return false;
-		}
-		
-		if(n_ready >= len + 1)
-			break;
-			
-		end = std::chrono::steady_clock::now();
-		elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
-	}
-	if(elapsed >= timeout)
-	{
-		std::cout << PRE << "block timeout: " << std::endl;
-		return false;
-	}
-	
-	while(len--)
-	{
-		*buffer = readByte();
-		
-		crc ^= *buffer++;
-		for (uint8_t i = 0; i < 8; i++)
-		{
-			if (crc & 1)
-				crc ^= CRC7_POLY;
-			crc >>= 1;
-		}
-	}
-	
-	crc ^= readByte();
-	for (uint8_t i = 0; i < 8; i++)
-	{
-		if (crc & 1)
-			crc ^= CRC7_POLY;
-		crc >>= 1;
-	}
-	
-	if(TEST == 1)
-		crc = 1;
-	if(TEST > 100)
-		TEST = 0;
-	
-	if (crc == 0)
-	{
-		writeByte(MSG_OK);
-		return true;
-	}
-	else
-	{
-		writeByte(MSG_FAIL);
-		return false;
-	}
-}
-
 void B15F::delay_ms(uint16_t ms)
 {
 	std::this_thread::sleep_for(std::chrono::milliseconds(ms));
diff --git a/drv/b15f.h b/drv/b15f.h
index 4d48b21..132c4c8 100644
--- a/drv/b15f.h
+++ b/drv/b15f.h
@@ -14,6 +14,7 @@
 #include <fcntl.h>
 #include <sys/ioctl.h>
 #include <termios.h>
+#include "usart.h"
 #include "driverexception.h"
 #include "timeoutexception.h"
 
@@ -59,35 +60,12 @@ public:
 	static B15F& getInstance(void);
 
 private:
-	int usart = -1;
 	uint16_t timeout = 1000; // ms
 	uint16_t block_timeout = 1; // ms
-	int TEST = 0;
+	USART usart;
 
 	static B15F* instance;
 	
-	
-	/***********************************************
-	 * Grundfunktionen für die serielle Verbindung *
-	 ***********************************************/
-	
-	/**
-	 * Übergibt ein Byte an die USART Schnittstelle
-	 */
-	void writeByte(uint8_t);
-	
-	/**
-	 * Übergibt ein Integer an die USART Schnittstelle
-	 */
-	void writeInt(uint16_t);
-	
-	/**
-	 * Übergibt ein Integer an die USART Schnittstelle
-	 * \throws TimeoutException
-	 */
-	uint8_t readByte(void);
-	uint16_t readInt(void);
-	bool readBlock(uint8_t* buffer, uint16_t offset);
 
 
 	// CONSTANTS
@@ -98,7 +76,6 @@ private:
 	constexpr static uint16_t RECONNECT_TIMEOUT = 64; // ms
 	constexpr static uint8_t  RECONNECT_TRIES = 3;
 	constexpr static uint32_t BAUDRATE = 115200;
-	constexpr static uint8_t  CRC7_POLY = 0x91;
 	
 	// REQUESTS
 	constexpr static uint8_t RQ_DISC = 0;
diff --git a/drv/b15f.o b/drv/b15f.o
index 47f3a9c..5b6d8ec 100644
Binary files a/drv/b15f.o and b/drv/b15f.o differ
diff --git a/drv/usart.cpp b/drv/usart.cpp
index 554c598..5760d8e 100644
--- a/drv/usart.cpp
+++ b/drv/usart.cpp
@@ -1,10 +1,6 @@
 #include "usart.h"
 
-USART::USART(std::string device) : device(device)
-{
-}
-
-void USART::openDevice()
+void USART::openDevice(std::string device)
 {
 	file_desc = open(device.c_str(), O_RDWR | O_NOCTTY | O_NDELAY);
 	if(file_desc <= 0)
@@ -53,6 +49,127 @@ void USART::clearOutputBuffer()
 		throw USARTException("Fehler beim Leeren des Ausgangspuffers");
 }
 
+void USART::writeByte(uint8_t b)
+{
+	if(write(file_desc, &b, 1) != 1)
+		throw USARTException("Fehler beim Senden: writeByte()");
+}
+	
+void USART::writeInt(uint16_t d)
+{
+	if(write(file_desc, reinterpret_cast<char*>(&d), 2) != 2)
+		throw USARTException("Fehler beim Senden: writeInt()");
+}
+	
+uint8_t USART::readByte(void)
+{
+	char b;
+	auto start = std::chrono::steady_clock::now();
+	auto end = start;
+	uint16_t elapsed = 0;
+	while(elapsed < timeout)
+	{
+		int n_ready;
+		int code = ioctl(file_desc, FIONREAD, &n_ready);
+		if(code != 0)
+				std::cout << "n_ready code: " << code << std::endl;
+		
+		if(n_ready > 0)
+		{				
+			//std::cout << code << " \tready: " << n_ready << std::endl;
+			
+			code = read(file_desc, &b, 1);
+			if (code > 0)
+				return static_cast<uint8_t>(b);
+			if (code < 0)
+				std::cout << "usart code: " << code << std::endl;
+		}
+		
+		end = std::chrono::steady_clock::now();
+		elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
+	}
+	
+	if(elapsed >= timeout)
+		throw USARTException("Verbindung unterbrochen. (timeout)");
+}
+
+uint16_t USART::readInt(void)
+{
+	return readByte() | readByte() << 8;
+}
+
+bool USART::readBlock(uint8_t* buffer, uint16_t offset)
+{
+	uint8_t len = readByte();
+	uint8_t crc = 0;
+	buffer += offset;
+	
+	uint32_t block_timeout = timeout / 10;
+	
+	// wait for block
+	int n_ready;
+	uint16_t elapsed = 0;
+	auto start = std::chrono::steady_clock::now();
+	auto end = start;
+	while(elapsed < block_timeout)
+	{
+		int code = ioctl(file_desc, FIONREAD, &n_ready);
+		if(code != 0)
+		{
+			std::cout <<  "n_ready code: " << code << std::endl;
+			return false;
+		}
+		
+		if(n_ready >= len + 1)
+			break;
+			
+		end = std::chrono::steady_clock::now();
+		elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
+	}
+	if(elapsed >= timeout)
+	{
+		std::cout  << "block timeout: " << std::endl;
+		return false;
+	}
+	
+	while(len--)
+	{
+		*buffer = readByte();
+		
+		crc ^= *buffer++;
+		for (uint8_t i = 0; i < 8; i++)
+		{
+			if (crc & 1)
+				crc ^= CRC7_POLY;
+			crc >>= 1;
+		}
+	}
+	
+	crc ^= readByte();
+	for (uint8_t i = 0; i < 8; i++)
+	{
+		if (crc & 1)
+			crc ^= CRC7_POLY;
+		crc >>= 1;
+	}
+	
+	if(TEST == 1)
+		crc = 1;
+	if(TEST > 100)
+		TEST = 0;
+	
+	if (crc == 0)
+	{
+		writeByte(0xFF);
+		return true;
+	}
+	else
+	{
+		writeByte(0xFE);
+		return false;
+	}
+}
+
 uint32_t USART::getBaudrate()
 {
 	return baudrate;
diff --git a/drv/usart.h b/drv/usart.h
index 7d17d20..a23cab1 100644
--- a/drv/usart.h
+++ b/drv/usart.h
@@ -1,7 +1,9 @@
 #ifndef USART_H
 #define USART_H
 
+#include <iostream>
 #include <cstdint>
+#include <chrono>
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/ioctl.h>
@@ -11,7 +13,6 @@
 class USART
 {
 public:
-	USART(std::string device);
 	
 	/*************************************************
 	 * Methoden für die Verwaltung der Schnittstelle *
@@ -19,9 +20,10 @@ public:
 	
 	/**
 	 * Öffnet die USART Schnittstelle
+	 * \param device Linux-Gerätepfad
 	 * \throws USARTException 
 	 */
-	void openDevice(void);
+	void openDevice(std::string device);
 	
 	/**
 	 * Schließt die USART Schnittstelle
@@ -56,6 +58,17 @@ public:
 	 */
 	void writeByte(uint8_t b);
 	
+	/**
+	 * Sendet ein Integer über die USART Schnittstelle
+	 * \param b das zu sendende Byte
+	 * \throws USARTException 
+	 */
+	void writeInt(uint16_t d);
+	
+	uint8_t readByte(void);
+	uint16_t readInt(void);
+	bool readBlock(uint8_t* buffer, uint16_t offset);
+	
 	/*************************************/
 	
 	
@@ -92,10 +105,12 @@ public:
 	
 private:
 	
-	std::string device; // Gerätepfad
 	int file_desc = -1; // Linux Dateideskriptor
 	uint32_t baudrate = 9600;
+	int TEST = 0;
 	uint8_t timeout = 10; // in Dezisekunden
+	
+	constexpr static uint8_t  CRC7_POLY = 0x91;
 };
 
 
diff --git a/drv/usart.o b/drv/usart.o
index 3039e27..da366a5 100644
Binary files a/drv/usart.o and b/drv/usart.o differ
diff --git a/main b/main
index da5b077..36cd534 100755
Binary files a/main and b/main differ
diff --git a/main.cpp b/main.cpp
index 6f27b98..5293528 100644
--- a/main.cpp
+++ b/main.cpp
@@ -182,8 +182,9 @@ void beispielFunktionen()
 int main()
 {
 	
-	USART usart("/dev/ttyUSB0");
-	usart.openDevice();
+	USART usart;
+	usart.openDevice("/dev/ttyUSB0");
+	usart.closeDevice();
 	
 	
 	
diff --git a/main.o b/main.o
index 551fea6..e53cb55 100644
Binary files a/main.o and b/main.o differ