diff --git a/src/Mod/Fem/femsolver/settings.py b/src/Mod/Fem/femsolver/settings.py
index 4e6ec51bf3..22e455dcc3 100644
--- a/src/Mod/Fem/femsolver/settings.py
+++ b/src/Mod/Fem/femsolver/settings.py
@@ -1,5 +1,6 @@
 # ***************************************************************************
 # *   Copyright (c) 2017 Markus Hovorka <m.hovorka@live.de>                 *
+# *   Copyright (c) 2019 Bernd Hahnebach <bernd@bimstatik.org>              *
 # *                                                                         *
 # *   This program is free software; you can redistribute it and/or modify  *
 # *   it under the terms of the GNU Lesser General Public License (LGPL)    *
@@ -20,28 +21,34 @@
 # ***************************************************************************
 
 __title__ = "FreeCAD FEM solver settings"
-__author__ = "Markus Hovorka"
+__author__ = "Markus Hovorka, Bernd Hahnebach"
 __url__ = "http://www.freecadweb.org"
 
 ## \addtogroup FEM
 #  @{
 
-import distutils.spawn
+'''
+parameter in FreeCAD can be edited in two ways, either in the
+Preferences: menu Edit --> Preferences
+or
+Parameter editor: menu Tools --> Edit parameter
+'''
+
 import FreeCAD
 
 
+# working directory: possible choices
 TEMPORARY = "temporary"
 BESIDE = "beside"
 CUSTOM = "custom"
 
 
+# FEM parameter location path
 _PARAM_PATH = "User parameter:BaseApp/Preferences/Mod/Fem/"
 _GENERAL_PARAM = _PARAM_PATH + "General"
-_CCX_PARAM = _PARAM_PATH + "Ccx"
-_ELMER_PARAM = _PARAM_PATH + "Elmer"
-_Z88_PARAM = _PARAM_PATH + "Z88"
 
 
+# ******** binary parameter **********************************************************************
 class _BinaryDlg(object):
 
     def __init__(self, default, param, useDefault, customPath):
@@ -51,34 +58,58 @@ class _BinaryDlg(object):
         self.customPath = customPath
 
     def getBinary(self):
+
+        # get the parameter object where the paramete are saved in
         paramObj = FreeCAD.ParamGet(self.param)
+
+        # set the binary path to the FreeCAD defaults, ATM pure unix shell commands without path names are used
+        # TODO see todo on useDefault later in this module
         binary = self.default
         FreeCAD.Console.PrintLog('Solver binary path: {} \n'.format(binary))
+
+        # check if useDefault is set to True
+        # if True the standard binary path will be overwritten with a user binary path
         if not paramObj.GetBool(self.useDefault, True):
             binary = paramObj.GetString(self.customPath)
         FreeCAD.Console.PrintLog('Solver binary path: {} \n'.format(binary))
-        return distutils.spawn.find_executable(binary)
+
+        # get the whole binary path name for the given command or binary path and return it
+        from distutils.spawn import find_executable as find_bin
+        return find_bin(binary)
 
 
+'''
+default:
+    default command to run the binary, this one is taken if the UseStandardXXXLocation is not given or set to True
+param:
+    path where these settings are saved, in FEM normally one path in one Tab in Preferences GUI
+useDefault:
+    the UseStandardXXXLocation parameter identifier
+    if this parameter is set to True FreeCAD standards for the binary are used, or FreeCAD tries to find the binary
+    TODO: see method setup_ccx in ccx tools module, which sets up ccx binary for various os
+customPath:
+    the xxxBinaryPath parameter identifier
+    binary path given by the user
+'''
 _BINARIES = {
     "Calculix": _BinaryDlg(
         default="ccx",
-        param=_CCX_PARAM,
+        param=_PARAM_PATH + "Ccx",
         useDefault="UseStandardCcxLocation",
         customPath="ccxBinaryPath"),
     "ElmerSolver": _BinaryDlg(
         default="ElmerSolver",
-        param=_ELMER_PARAM,
+        param=_PARAM_PATH + "Elmer",
         useDefault="UseStandardElmerLocation",
         customPath="elmerBinaryPath"),
     "ElmerGrid": _BinaryDlg(
         default="ElmerGrid",
-        param=_ELMER_PARAM,
+        param=_PARAM_PATH + "Elmer",
         useDefault="UseStandardGridLocation",
         customPath="gridBinaryPath"),
     "Z88": _BinaryDlg(
         default="z88r",
-        param=_Z88_PARAM,
+        param=_PARAM_PATH + "Z88",
         useDefault="UseStandardZ88Location",
         customPath="z88BinaryPath"),
 }
@@ -96,6 +127,7 @@ def getBinary(name):
         return None
 
 
+# ******** working directory parameter ***********************************************************
 def getCustomDir():
     param = FreeCAD.ParamGet(_GENERAL_PARAM)
     return param.GetString("CustomDirectoryPath")