diff --git a/tests/gcodeSender.py b/tests/gcodeSender.py
new file mode 100755
index 000000000..cea75d336
--- /dev/null
+++ b/tests/gcodeSender.py
@@ -0,0 +1,79 @@
+#!/usr/bin/python
+#
+# A tool to send a GCODE file to Marlin via a serial or USB connection.
+#
+# This tool can also exercise error correction and recovery in Marlin by
+# corrupting a fraction of the GCODE packets that are sent.
+#
+
+#
+# (c) 2017 Aleph Objects, Inc.
+#
+# The code in this page is free software: you can
+# redistribute it and/or modify it under the terms of the GNU
+# General Public License (GNU GPL) as published by the Free Software
+# Foundation, either version 3 of the License, or (at your option)
+# any later version.  The code is distributed WITHOUT ANY WARRANTY;
+# without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU GPL for more details.
+#
+
+from __future__ import print_function
+from pyMarlin   import *
+
+import argparse
+import serial
+
+UseNoisySerial = True
+
+def load_gcode(filename):
+  with open(filename, "r") as f:
+    gcode = f.readlines()
+  print("Read %d lines" % len(gcode))
+  return gcode
+
+def send_gcode_test(filename, serial):
+  gcode = load_gcode("test.gco");
+
+  for i, line in enumerate(gcode):
+    serial.sendCommand(line)
+    while(not serial.clearToSend()):
+      serial.readLine()
+    if(i % 1000 == 0):
+      print("Progress: %d" % (i*100/len(gcode)), end='\r')
+
+parser = argparse.ArgumentParser(description='''sends gcode to a printer while injecting errors to test error recovery.''')
+parser.add_argument('-f', '--fake',   help='Use a fake Marlin simulation instead of serial port, for self-testing.', action='store_false', dest='port')
+parser.add_argument('-p', '--port',   help='Serial port.', default='/dev/ttyACM1')
+parser.add_argument('-e', '--errors', help='Corrupt 1 out N lines to exercise error recovery.', default='0', type=int)
+parser.add_argument('-l', '--log',    help='Write log file.')
+parser.add_argument('filename',       help='file containing gcode.')
+args = parser.parse_args()
+
+print()
+
+if args.port:
+  print("Serial port: ", args.port)
+  sio = serial.Serial(args.port, 115000, timeout = 3, writeTimeout = 10000)
+else:
+  print("Using simulated Marlin device.")
+  sio = FakeMarlinSerialDevice()
+
+if args.log:
+  print("Writing log file: ", args.log)
+  chatty = LoggingSerialConnection(sio, args.log)
+else:
+  chatty = sio
+
+if args.errors:
+  print("1 out of %d lines will be corrupted." % args.errors)
+  noisy = NoisySerialConnection(chatty)
+  noisy.setErrorRate(1, args.errors)
+else:
+  noisy = chatty
+
+print()
+
+proto = MarlinSerialProtocol(noisy)
+send_gcode_test(args.filename, proto)
+proto.close()
\ No newline at end of file
diff --git a/tests/pyMarlin/__init__.py b/tests/pyMarlin/__init__.py
new file mode 100644
index 000000000..4adfbfe46
--- /dev/null
+++ b/tests/pyMarlin/__init__.py
@@ -0,0 +1,7 @@
+from pyMarlin.loggingSerialConnection import LoggingSerialConnection
+from pyMarlin.noisySerialConnection   import NoisySerialConnection
+from pyMarlin.loggingSerialConnection import LoggingSerialConnection
+from pyMarlin.marlinSerialProtocol    import MarlinSerialProtocol
+from pyMarlin.fakeMarlinSerialDevice  import FakeMarlinSerialDevice
+
+__all__ = ['LoggingSerialConnection','NoisySerialConnection','MarlinSerialProtocol','FakeMarlinSerialDevice']
diff --git a/tests/pyMarlin/fakeMarlinSerialDevice.py b/tests/pyMarlin/fakeMarlinSerialDevice.py
new file mode 100644
index 000000000..59fab73cc
--- /dev/null
+++ b/tests/pyMarlin/fakeMarlinSerialDevice.py
@@ -0,0 +1,84 @@
+#
+# (c) 2017 Aleph Objects, Inc.
+#
+# The code in this page is free software: you can
+# redistribute it and/or modify it under the terms of the GNU
+# General Public License (GNU GPL) as published by the Free Software
+# Foundation, either version 3 of the License, or (at your option)
+# any later version.  The code is distributed WITHOUT ANY WARRANTY;
+# without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU GPL for more details.
+#
+
+import functools
+import random
+import string
+import re
+
+class FakeMarlinSerialDevice:
+  """This serial class simply pretends to be Marlin by acknowledging
+     commands with "ok" and requesting commands to be resent if they
+     contain errors"""
+
+  def __init__(self):
+    self.line      = 1
+    self.replies   = []
+    self.pendingOk = 0
+
+    self.cumulativeReads     = 0
+    self.cumulativeWrites    = 0
+    self.cumulativeQueueSize = 0
+    self.cumulativeErrors    = 0
+
+  def _enqueue_reply(self, str):
+    if str == b"ok":
+      self.pendingOk += 1
+    self.replies.append(str + '\n')
+
+  def _dequeue_reply(self):
+    if len(self.replies):
+      reply = self.replies.pop(0)
+      if reply == b"ok\n":
+        self.pendingOk -= 1
+      return reply
+    else:
+      return ''
+
+  def _computeChecksum(self, data):
+    """Computes the GCODE checksum, this is the XOR of all characters in the payload, including the position"""
+    return functools.reduce(lambda x,y: x^y, map(ord, data))
+
+  def write(self, data):
+    m = re.match('N(\d+)(\D[^*]*)\*(\d*)$', data)
+    if m and int(m.group(1)) == self.line and self._computeChecksum("N%d%s" % (self.line, m.group(2))) == int(m.group(3)):
+      # We have a valid, properly sequenced command with a valid checksum
+      self.line += 1
+    else:
+      # Otherwise, request the command be resent
+      self.cumulativeErrors += 1
+      self.replies   = []
+      self.pendingOk = 0
+      self._enqueue_reply("Resend: " + str(self.line))
+
+    for i in range(0,random.randint(0,4)):
+      # Simulate a command that takes a while to execute
+      self._enqueue_reply("")
+    self._enqueue_reply("ok")
+
+    self.cumulativeWrites     += 1
+    self.cumulativeQueueSize  += self.pendingOk
+
+  def readline(self):
+    self.cumulativeReads      += 1
+    return self._dequeue_reply()
+
+  def flush(self):
+    pass
+
+  def close(self):
+    print "Average length of commands queue: %.2f" % (float(self.cumulativeQueueSize) / self.cumulativeWrites)
+    print "Average reads per write:          %.2f" % (float(self.cumulativeReads)     / self.cumulativeWrites)
+    print "Average errors per write:         %.2f" % (float(self.cumulativeErrors)    / self.cumulativeWrites)
+    print "Total writes:                     %d"   % self.cumulativeWrites
+    print "Total errors:                     %d"   % self.cumulativeErrors
+    print
diff --git a/tests/pyMarlin/loggingSerialConnection.py b/tests/pyMarlin/loggingSerialConnection.py
new file mode 100644
index 000000000..c01104fff
--- /dev/null
+++ b/tests/pyMarlin/loggingSerialConnection.py
@@ -0,0 +1,45 @@
+#
+# (c) 2017 Aleph Objects, Inc.
+#
+# The code in this page is free software: you can
+# redistribute it and/or modify it under the terms of the GNU
+# General Public License (GNU GPL) as published by the Free Software
+# Foundation, either version 3 of the License, or (at your option)
+# any later version.  The code is distributed WITHOUT ANY WARRANTY;
+# without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU GPL for more details.
+#
+
+from __future__ import print_function
+
+import sys
+
+class LoggingSerialConnection:
+  """Wrapper class which prints the input and output from a serial connection"""
+  def __init__(self, serial, filename):
+    self.serial     = serial
+    self.verbose    = True
+    self.file       = open(filename, 'w+')
+
+  def _log(self, *args, **kwargs):
+    if(self.verbose):
+      print(*args, file=self.file, **kwargs)
+      self.file.flush()
+
+  def write(self, data):
+    self._log("> " + data, end='')
+    self.serial.write(data)
+
+  def flush(self):
+    self.serial.flush()
+
+  def close(self):
+    self.serial.close()
+
+  def readline(self):
+    data = self.serial.readline()
+    if(data == b""):
+      self._log("< Timeout")
+    else:
+      self._log("< " + data, end='')
+    return data
\ No newline at end of file
diff --git a/tests/pyMarlin/marlinSerialProtocol.py b/tests/pyMarlin/marlinSerialProtocol.py
new file mode 100644
index 000000000..9e3363c78
--- /dev/null
+++ b/tests/pyMarlin/marlinSerialProtocol.py
@@ -0,0 +1,191 @@
+#
+# (c) 2017 Aleph Objects, Inc.
+#
+# The code in this page is free software: you can
+# redistribute it and/or modify it under the terms of the GNU
+# General Public License (GNU GPL) as published by the Free Software
+# Foundation, either version 3 of the License, or (at your option)
+# any later version.  The code is distributed WITHOUT ANY WARRANTY;
+# without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU GPL for more details.
+#
+
+# Marlin implements an error correcting scheme on the serial connections.
+# GCode commands are sent with a line number and a checksum. If Marlin
+# detects an error, it requests that the transmission resume from the
+# last known good line number.
+#
+# In addition to this resend mechanism, Marlin also implements flow
+# control. Sent commands are acknowleged by "ok" when complete.
+# However, to optimize path planning, Marlin contains a command
+# buffer and slicing software should send enough commands to keep
+# that buffer filled (minus a reserve capacity for emergency commands
+# such as an emergency STOP). It is thus necessary to send a certain
+# number prior the earlier ones being acknowleged and to track how
+# many commands have been sent but not yet acknowleged.
+#
+# The class MarlinSerialProtocol implements the error correction
+# and also manages acknowlegements and flow control.
+#
+# The prototypical use case for this class is as follows:
+#
+#   for line in enumerate(gcode):
+#     serial.sendCommand(line)
+#     while(not serial.clearToSend()):
+#       serial.readLine()
+#
+
+import functools
+
+class GCodeHistory:
+  """This class implements a history of GCode commands. Right now, we
+     keep the entire history, but this probably could be reduced to a
+     smaller range. This class keeps a pointer to the position of
+     the first unsent command, which typically is the one just recently
+     appended, but after a resend request from Marlin that position can
+     rewound to further back."""
+  def __init__(self):
+    self.clear()
+
+  def clear(self):
+    self.list = [None] # Pad so the first element is at index 1
+    self.pos  = 1
+
+  def append(self, cmd):
+    self.list.append(cmd)
+
+  def rewindTo(self, position):
+    self.pos = max(1,min(position, len(self.list)))
+
+  def getAppendPosition(self):
+    """Returns the position at which the next append will happen"""
+    return len(self.list)
+
+  def getNextCommand(self):
+    """Returns the next unsent command."""
+    if(not self.atEnd()):
+      res = self.pos, self.list[self.pos]
+      self.pos += 1;
+      return res
+
+  def atEnd(self):
+    return self.pos == len(self.list)
+
+class MarlinSerialProtocol:
+  """This class implements the Marlin serial protocol, such
+  as adding a checksum to each line, replying to resend
+  requests and keeping the Marlin buffer full"""
+  def __init__(self, serial):
+    self.serial                 = serial
+    self.marlinBufSize          = 4
+    self.marlinReserve          = 1
+    self.pendingOk              = 0
+    self.history                = GCodeHistory()
+    self.restart()
+
+  def _stripCommentsAndWhitespace(self, str):
+    return str.split(';', 1)[0].strip()
+
+  def _replaceEmptyLineWithM105(self, str):
+    """Marlin will not accept empty lines, so replace blanks with M115 (Get Extruder Temperature)"""
+    return "M105" if str == "" else str
+
+  def _computeChecksum(self, data):
+    """Computes the GCODE checksum, this is the XOR of all characters in the payload, including the position"""
+    return functools.reduce(lambda x,y: x^y, map(ord, data))
+
+  def _addPositionAndChecksum(self, position, cmd):
+    """An GCODE with line number and checksum consists of N{position}{cmd}*{checksum}"""
+    data = "N%d%s"    % (position, cmd)
+    return "N%d%s*%d" % (position, cmd, self._computeChecksum(data))
+
+  def _sendToMarlin(self):
+    """Sends as many commands as are available and to fill the Marlin buffer.
+       Commands are read from the history. Generally only the most recently
+       appended command is sent; but after a resend request, we may be
+       further back in the history than that"""
+    while(not self.history.atEnd() and self.marlinBufferCapacity() > 0):
+      pos, cmd = self.history.getNextCommand();
+      self.serial.write(cmd + '\n')
+      self.serial.flush()
+      self.pendingOk += 1
+
+  def _isResend(self, line):
+    """If the line is a resend command from Marlin, returns the line number. This
+       code was taken from Cura 1, I do not know why it is so convoluted."""
+    if "resend" in line.lower() or "rs" in line:
+      try:
+        return int(line.replace("N:"," ").replace("N"," ").replace(":"," ").split()[-1])
+      except:
+        if "rs" in line:
+          return int(line.split()[1])
+
+  def _resendFrom(self, position):
+    """If Marlin requests a resend, we need to backtrack."""
+    self.history.rewindTo(position)
+    self.pendingOk    = 1
+
+    # When receive a resend request, we must temporarily
+    # switch to sending commands one at a time, otherwise
+    # buffering could lead to additional errors, which
+    # cause Marlin to send more resend requests and
+    # to us never recovering.
+    self.resyncCountdown = self.marlinBufSize
+
+  def _flushReadBuffer(self):
+    while self.serial.readline() != b"":
+      pass
+
+  def sendCommand(self, cmd):
+    """Sends a command. Should only be called if clearToSend() is true"""
+    cmd = self._stripCommentsAndWhitespace(cmd)
+    cmd = self._replaceEmptyLineWithM105(cmd)
+    cmd = self._addPositionAndChecksum(self.history.getAppendPosition(), cmd)
+    # Add command to the history, but immediately send it out.
+    self.history.append(cmd)
+    self._sendToMarlin()
+
+  def readLine(self):
+    """This reads data from Marlin. If no data is available '' will be returned after
+       the comm timeout. This *must* be called periodically to keep outgoing data moving
+       from the buffers."""
+    self._sendToMarlin()
+    line = self.serial.readline()
+    if self._isResend(line):
+      # When a resend is requested, handle it.
+      # Return blank to caller.
+      position = self._isResend(line)
+      self._resendFrom(position)
+      line = b""
+    elif line.startswith(b"ok"):
+      self.pendingOk -= 1
+      # Decrement the resync countdown so we
+      # can eventually return to buffered mode
+      if self.resyncCountdown > 0:
+        self.resyncCountdown -= 1
+
+    return line
+
+  def clearToSend(self):
+      self._sendToMarlin()
+      return self.marlinBufferCapacity() > 0
+
+  def marlinBufferCapacity(self):
+    """Returns how many buffer positions are open in Marlin. This is the difference between
+       the non-reserved buffer spots and the number of not yet acknowleged commands"""
+    if self.resyncCountdown > 0:
+      # If we are have recently received a resend request, go
+      # into unbuffered line-by-line mode temporarily.
+      return 0 if self.pendingOk else 1
+    else:
+      return (self.marlinBufSize - self.marlinReserve) - self.pendingOk
+
+  def restart(self):
+    """Clears all buffers and issues a M110 to Marlin. Call this at the start of every print."""
+    self. _flushReadBuffer()
+    self.resyncCountdown = self.marlinBufSize
+    self.history.clear()
+    self.sendCommand(b"M110")
+
+  def close(self):
+    self.serial.close()
\ No newline at end of file
diff --git a/tests/pyMarlin/noisySerialConnection.py b/tests/pyMarlin/noisySerialConnection.py
new file mode 100644
index 000000000..b9e069535
--- /dev/null
+++ b/tests/pyMarlin/noisySerialConnection.py
@@ -0,0 +1,44 @@
+#
+# (c) 2017 Aleph Objects, Inc.
+#
+# The code in this page is free software: you can
+# redistribute it and/or modify it under the terms of the GNU
+# General Public License (GNU GPL) as published by the Free Software
+# Foundation, either version 3 of the License, or (at your option)
+# any later version.  The code is distributed WITHOUT ANY WARRANTY;
+# without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU GPL for more details.
+#
+
+import random
+import string
+
+class NoisySerialConnection:
+  """Wrapper class which injects character noise into the outgoing packets
+     of a serial connection for testing Marlin's error correction"""
+  def __init__(self, serial):
+    self.serial     = serial
+    self.errorRate  = 0
+
+  def _corruptStr(self, str):
+    """Introduces a single character error on a string"""
+    charToCorrupt = random.randint(0, len(str) - 1)
+    return str[:charToCorrupt] + random.choice(string.ascii_letters) + str[charToCorrupt+1:]
+
+  def write(self, data):
+    if(random.random() < self.errorRate):
+      data = self._corruptStr(data)
+    self.serial.write(data)
+
+  def readline(self):
+    return self.serial.readline()
+
+  def flush(self):
+    self.serial.flush()
+
+  def close(self):
+    self.serial.close()
+
+  def setErrorRate(self, badWrites, totalWrites):
+    """Inserts a single character error into every badWrites out of totalWrites"""
+    self.errorRate = float(badWrites)/float(totalWrites)
\ No newline at end of file