diff --git a/lib/tdm_reaper.cpp b/lib/tdm_reaper.cpp
index 778b017..251335d 100644
--- a/lib/tdm_reaper.cpp
+++ b/lib/tdm_reaper.cpp
@@ -4,10 +4,37 @@
 
 // -------------------------------------------------------------------------- //
 
-tdm_ripper::tdm_ripper(std::string tdmfile, std::string tdxfile,
-                       bool suppress_status, bool neglect_empty_groups)
+tdm_ripper::tdm_ripper(std::string tdmfile, std::string tdxfile, bool showlog):
+  tdmfile_(tdmfile), tdxfile_(tdxfile)
 {
+  // check both tdm, tdx files
+  std::filesystem::path ptdm(tdmfile_), ptdx(tdxfile_);
+  if ( !std::filesystem::exists(ptdm) )
+  {
+    throw std::runtime_error(std::string("*.tdm file ") + tdmfile_ + " does not exist!");
+  }
+  if ( !std::filesystem::exists(ptdx) )
+  {
+    throw std::runtime_error(std::string("*.tdx file ") + tdxfile_ + " does not exist!");
+  }
 
+  // set up xml-parser and load tdm file
+  try {
+    xml_result_ = xml_doc_.load_file(tdmfile_.c_str());
+
+    if ( !showlog )
+    {
+      std::cout<<"loading and parsing file: "<<xml_result_.description()<<"\n";
+      std::cout<<"encoding: "<<(pugi::xml_encoding)xml_result_.encoding<<"\n";
+    }
+
+  } catch (const std::exception& e) {
+    throw std::runtime_error(std::string("failed to load tdm file: ") + e.what());
+  }
+
+  pugi::xml_node xmlusiincl = xml_doc_.child("usi:tdm").child("usi:include");
+  pugi::xml_node xmlusidata = xml_doc_.child("usi:tdm").child("usi:data");
+  pugi::xml_node xmltdmroot = xml_doc_.child("usi:tdm").child("usi:data").child("tdm_root");
 
 }
 
diff --git a/lib/tdm_reaper.hpp b/lib/tdm_reaper.hpp
index ea28070..e56a101 100644
--- a/lib/tdm_reaper.hpp
+++ b/lib/tdm_reaper.hpp
@@ -13,23 +13,167 @@
 #include <map>
 #include <numeric>
 #include <algorithm>
+#include <chrono>
+#include <sstream>
+#include <filesystem>
 
 #include "pugixml.hpp"
 
 // -------------------------------------------------------------------------- //
 // define datatypes
 
+// https://zone.ni.com/reference/de-XX/help/370858P-0113/tdmdatamodel/tdmdatamodel/tdm_header_tdx_data/
+
+enum class tdm_datatype {
+  eInt16Usi,
+  eInt32Usi,
+  //
+  eUInt8Usi,
+  eUInt16Usi,
+  eUInt32Usi,
+  //
+  eFloat32Usi,
+  eFloat64Usi,
+  //
+  eStringUsi
+};
+
 struct datatype {
   std::string name_;
   std::string channel_datatype_;
   int numeric_;
   std::string value_sequence_;
   int size_;
-  std::string description;
+  std::string description_;
+
+  std::string get_info()
+  {
+    std::stringstream ss;
+    ss<<"name:             "<<name_<<"\n"
+      <<"channel_datatype: "<<channel_datatype_<<"\n"
+      <<"numeric:          "<<numeric_<<"\n"
+      <<"value_sequence:   "<<value_sequence_<<"\n"
+      <<"size:             "<<size_<<"\n"
+      <<"description:      "<<description_<<"\n";
+    return ss.str();
+  }
 };
 
 const std::map<std::string,datatype> tdm_datatypes = {
-  {"eInt16Usi",{"eInt16Usi","DT_SHORT",2,"short_sequence",2,"signed 16 bit integer"}}
+
+  {"eInt16Usi",{"eInt16Usi","DT_SHORT",2,"short_sequence",2,"signed 16 bit integer"}},
+  {"eInt32Usi",{"eInt32Usi","DT_LONG",6,"long_sequence",4,"signed 32 bit integer"}},
+
+  {"eUInt8Usi",{"eUInt8Usi","DT_BYTE",5,"byte_sequence",1,"unsigned 8 bit integer"}},
+  {"eUInt16Usi",{"eUInt16Usi","DT_SHORT",2,"short_sequence",2,"unsigned 16 bit integer"}},
+  {"eUInt32Usi",{"eUInt32Usi","DT_LONG",6,"long_sequence",4,"unsigned 32 bit integer"}},
+
+  {"eFloat32Usi",{"eFloat32Usi","DT_FLOAT",3,"float_sequence",4,"32 bit float"}},
+  {"eFloat64Usi",{"eFloat64Usi","DT_DOUBLE",7,"double_sequence",8,"64 bit double"}},
+
+  {"eStringUsi",{"eStringUsi","DT_STRING",1,"string_sequence",0,"text"}}
+
+};
+
+// -------------------------------------------------------------------------- //
+// tdm root, tdm group and tdm channel, etc.
+
+// for reference of the tdm data model, see
+// https://zone.ni.com/reference/de-XX/help/370858P-0113/tdmdatamodel/tdmdatamodel/tdm_headerfile/
+// https://zone.ni.com/reference/de-XX/help/370858P-0113/tdmdatamodel/tdmdatamodel/tdm_datamodel/
+
+struct tdm_root {
+  std::string name_;
+  std::string description_;
+  std::string title_;
+  std::string author_;
+  std::string timestamp_;
+  // std::chrono::time_point timestamp_; // from string 2008-05-06T17:20:12.65074539184570313
+
+  // std::stringstream ss;
+  // ss<<"2008-05-06T17:20:12.65074539184570313";
+  // std::cout<<ss.str()<<"\n";
+  //
+  // std::chrono::time_point start = std::chrono::high_resolution_clock::now();
+  // std::time_t tt = std::chrono::system_clock::to_time_t(start);
+  // // https://en.cppreference.com/w/cpp/io/manip/put_time
+  // std::cout<<std::put_time(std::localtime(&tt),"%Y-%m-%dT%H:%M:%S")<<"\n";// "%F %T")<<"\n";
+  //
+  // // std::tm ts;
+  // // // https://en.cppreference.com/w/cpp/io/manip/get_time
+  // // std::get_time(&ts, "%Y-%m-%dT%H:%M:%S");
+  // // auto tp = std::chrono::system_clock::from_time_t(std::mktime(&ts));
+  // // std::time_t tt = std::chrono::system_clock::to_time_t(tp);
+  // // // std::cout<<tt.strftime("%Y")<<"\n";
+  // // std::cout<<ctime(&tt)<<"\n";
+
+  std::string channelgroups_;
+};
+
+// https://zone.ni.com/reference/de-XX/help/370858P-0113/tdmdatamodel/tdmdatamodel/tdm_metadata_chngroup/
+struct tdm_channelgroup {
+  unsigned long int id_;
+  std::string name_;
+  std::string description_;
+  long int rootid_;
+  std::vector<long int> channels_; // referenced by id
+};
+
+enum class wf_time_pref_type {
+  absolute,
+  relative
+};
+
+// additional elements for wave form channels (encoded as attributes in
+// <instance_attributes> of <tdm_channel>)
+// https://zone.ni.com/reference/de-XX/help/370858P-0113/tdmdatamodel/tdmdatamodel/tdm_tdxdata_waveform/
+struct waveform_channel {
+  std::string wf_xname_;
+  std::string wf_xunit_string_;
+  std::string wf_start_time_;
+  double wf_start_offset_;
+  double wf_increment_;
+  unsigned long wf_samples_;
+  wf_time_pref_type wf_time_pref;
+};
+
+// https://zone.ni.com/reference/de-XX/help/370858P-0113/tdmdatamodel/tdmdatamodel/tdm_metadata_channel/
+struct tdm_channel {
+  unsigned long int id_;
+  std::string name_;
+  std::string description_;
+  std::string unit_string_;
+  tdm_datatype datatype_;
+  double minimum_, maximum_;
+  unsigned long int groupd_id_;
+  waveform_channel wf_channel_;
+};
+
+// https://zone.ni.com/reference/de-XX/help/370858P-0113/tdmdatamodel/tdmdatamodel/tdm_tdxdata_submatrix/
+struct tdm_submatrix {
+  std::string name_;
+  unsigned long int number_of_rows_;
+  unsigned long int measurement_id_;
+  unsigned long int local_column_id_;
+};
+
+enum class representation {
+  explicit_,          // !! explicit is C++ keyword!!
+  implicit_linear_,   // datatype is always DT_DOUBLE, no <value_sequence> for implicit_linear_!!
+  raw_linear_         // datatype is always DT_DOUBLE
+};
+
+// https://zone.ni.com/reference/de-XX/help/370858P-0113/tdmdatamodel/tdmdatamodel/tdm_tdxdata_localcolumn/
+struct localcolumn {
+  std::string name_;
+  unsigned long int global_flag_;
+  unsigned long int independent_;
+  double minimum_, maximum_;
+  representation sequence_representation_;
+  std::vector<double> generation_parameters_; // { offset, factor }
+  unsigned long int measurement_quantity_id_;
+  unsigned long int submatrix_id_;
+  unsigned long int values_id_;
 };
 
 // -------------------------------------------------------------------------- //
@@ -47,6 +191,9 @@ class tdm_ripper
   // endianness (true = little, false = big)
   bool endianness_, machine_endianness_;
 
+  // tdm root
+  tdm_root tdmroot_;
+
   // number/names/ids of channels, channelgroups and channels's assignment to groups
   int num_channels_, num_groups_;
   std::vector<std::string> channel_id_, inc_id_, units_, channel_name_;
@@ -88,8 +235,7 @@ class tdm_ripper
 
 public:
 
-  tdm_ripper(std::string tdmfile, std::string tdxfile = "",
-             bool suppress_status = true, bool neglect_empty_groups = true);
+  tdm_ripper(std::string tdmfile, std::string tdxfile = std::string(""), bool showlog = false);
 
   void parse_structure();