diff --git a/Test cases.xlsx b/Test cases.xlsx
deleted file mode 100644
index da0c57a..0000000
Binary files a/Test cases.xlsx and /dev/null differ
diff --git a/Arduino/README_arduino.md b/src/arduino/README_arduino.md
similarity index 100%
rename from Arduino/README_arduino.md
rename to src/arduino/README_arduino.md
diff --git a/Arduino/__init__.py b/src/arduino/__init__.py
similarity index 100%
rename from Arduino/__init__.py
rename to src/arduino/__init__.py
diff --git a/Arduino/arduino.py b/src/arduino/arduino.py
similarity index 100%
rename from Arduino/arduino.py
rename to src/arduino/arduino.py
diff --git a/Arduino/prototype.ino b/src/arduino/prototype.ino
similarity index 100%
rename from Arduino/prototype.ino
rename to src/arduino/prototype.ino
diff --git a/cage_func.py b/src/cage_func.py
similarity index 98%
rename from cage_func.py
rename to src/cage_func.py
index da7dbb1..7ae72bb 100644
--- a/cage_func.py
+++ b/src/cage_func.py
@@ -8,9 +8,9 @@ import traceback
 from tkinter import messagebox
 
 # import other project files
-from User_Interface import ui_print
-from pyps2000b import PS2000B
-from Arduino import Arduino
+from user_interface import ui_print
+from ps2000b import PS2000B
+from arduino import Arduino
 import config_handling as config
 import globals as g
 
@@ -192,8 +192,8 @@ class ArduinoCtrl(Arduino):
                         axis.polarity_switched = "False"  # set attribute in axis object accordingly
             except Exception as e:  # some error occurred while trying to read status, usually arduino is disconnected
                 # show warning messages to alert user
-                ui_print("Error with Arduino:", e)
-                messagebox.showerror("Error with Arduino!", "Connection Error with Arduino: \n%s" % e)
+                ui_print("Error with arduino:", e)
+                messagebox.showerror("Error with arduino!", "Connection Error with arduino: \n%s" % e)
                 for axis in g.AXES:  # set polarity switch attributes in axis objects to "Unknown"
                     axis.polarity_switched = "Unknown"
                 self.connected = "Connection Error"  # update own connection status
@@ -347,7 +347,7 @@ def shut_down_all():  # safe shutdown at program end or on error
         ui_print("Z PSU not connected, can't deactivate.")
         message += "\nZ PSU not connected, can't deactivate."
 
-    # Shut down Arduino:
+    # Shut down arduino:
     try:
         g.ARDUINO.safe()  # call safe method in ArduinoCtrl class (all relay pins to LOW)
     except BaseException as e:  # some error occurred
diff --git a/config_handling.py b/src/config_handling.py
similarity index 99%
rename from config_handling.py
rename to src/config_handling.py
index 66ef1fd..3b49065 100644
--- a/config_handling.py
+++ b/src/config_handling.py
@@ -9,7 +9,7 @@ from tkinter import messagebox
 import globals as g
 import cage_func as func
 # noinspection PyPep8Naming
-import User_Interface as ui
+import user_interface as ui
 
 global CONFIG_FILE  # string storing the path of the used config file
 global CONFIG_OBJECT  # object of type ConfigParser(), storing all configuration information
diff --git a/csv_logging.py b/src/csv_logging.py
similarity index 98%
rename from csv_logging.py
rename to src/csv_logging.py
index a04636e..3f20df5 100644
--- a/csv_logging.py
+++ b/src/csv_logging.py
@@ -1,5 +1,5 @@
 # This file contains functions related to logging data from the program to a CSV file.
-# They are mainly but not only called by the ConfigureLogging class in User_Interface.py.
+# They are mainly but not only called by the ConfigureLogging class in user_interface.py.
 
 # import packages
 import pandas as pd
@@ -10,7 +10,7 @@ from tkinter import messagebox
 
 # import other project files
 import globals as g
-import User_Interface as ui
+import user_interface as ui
 
 log_data = pd.DataFrame()  # pandas data frame containing the logged data, in-program representation of csv/excel data
 unsaved_data = False  # Bool to indicate if there is unsaved data, set to True each time a datapoint is logged
diff --git a/csv_threading.py b/src/csv_threading.py
similarity index 99%
rename from csv_threading.py
rename to src/csv_threading.py
index 7793dcf..e98ee43 100644
--- a/csv_threading.py
+++ b/src/csv_threading.py
@@ -11,7 +11,7 @@ from tkinter import messagebox
 import matplotlib.pyplot as plt
 
 # import other project files:
-import User_Interface as ui
+import user_interface as ui
 import cage_func as func
 import globals as g
 
diff --git a/globals.py b/src/globals.py
similarity index 94%
rename from globals.py
rename to src/globals.py
index 46e8024..e38c910 100644
--- a/globals.py
+++ b/src/globals.py
@@ -44,8 +44,8 @@ default_arrays = {
 }
 # Dictionary for PSU serial ports:
 default_ports = {
-    "xy_port": "COM1",  # Default serial port where PSU for X- and Y-Axes is connected
-    "z_port": "COM2",  # Default serial port where PSU for Z-Axis is connected
+    "xy_port": "COM8",  # Default serial port where PSU for X- and Y-Axes is connected
+    "z_port": "COM5",  # Default serial port where PSU for Z-Axis is connected
 }
 
 # Configuration for socket interface
diff --git a/main.py b/src/main.py
similarity index 97%
rename from main.py
rename to src/main.py
index 40275c5..25421a8 100644
--- a/main.py
+++ b/src/main.py
@@ -7,9 +7,9 @@ from tkinter import messagebox
 
 # import other project files:
 import cage_func as func
-from User_Interface import HelmholtzGUI
-from User_Interface import ui_print
-import User_Interface as ui
+from user_interface import HelmholtzGUI
+from user_interface import ui_print
+import user_interface as ui
 import globals as g
 import config_handling as config
 import csv_logging as log
diff --git a/pyps2000b/LICENSE b/src/ps2000b/LICENSE
similarity index 100%
rename from pyps2000b/LICENSE
rename to src/ps2000b/LICENSE
diff --git a/pyps2000b/PS2000B.py b/src/ps2000b/PS2000B.py
similarity index 100%
rename from pyps2000b/PS2000B.py
rename to src/ps2000b/PS2000B.py
diff --git a/pyps2000b/README.md b/src/ps2000b/README.md
similarity index 100%
rename from pyps2000b/README.md
rename to src/ps2000b/README.md
diff --git a/pyps2000b/__init__.py b/src/ps2000b/__init__.py
similarity index 100%
rename from pyps2000b/__init__.py
rename to src/ps2000b/__init__.py
diff --git a/socket_control.py b/src/socket_control.py
similarity index 99%
rename from socket_control.py
rename to src/socket_control.py
index 24630c2..1de51c0 100644
--- a/socket_control.py
+++ b/src/socket_control.py
@@ -1,5 +1,5 @@
 import globals as g
-from User_Interface import ui_print
+from user_interface import ui_print
 import cage_func as cage_controls
 
 from threading import Thread
diff --git a/User_Interface.py b/src/user_interface.py
similarity index 100%
rename from User_Interface.py
rename to src/user_interface.py
diff --git a/test.csv b/test.csv
deleted file mode 100644
index dfe124f..0000000
--- a/test.csv
+++ /dev/null
@@ -1,4 +0,0 @@
-Date;Time;t (s);X PSU Status;Y PSU Status;Z PSU Status;X Voltage Setpoint;Y Voltage Setpoint;Z Voltage Setpoint;X Actual Voltage;Y Actual Voltage;Z Actual Voltage;X Current Setpoint;Y Current Setpoint;Z Current Setpoint;X Actual Current;Y Actual Current;Z Actual Current;X Target Field;Y Target Field;Z Target Field;X Trgt. Field Raw;Y Trgt. Field Raw;Z Trgt. Field Raw;X Target Current;Y Target Current;Z Target Current;X Inverted;Y Inverted;Z Inverted
-2021-03-22;10:58:32,248216;0,0;Not Connected;Not Connected;Not Connected;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;Unknown;Unknown;Unknown
-2021-03-22;10:58:33,262910;1,014694;Not Connected;Not Connected;Not Connected;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;Unknown;Unknown;Unknown
-2021-03-22;10:58:34,271188;2,022972;Not Connected;Not Connected;Not Connected;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;Unknown;Unknown;Unknown