diff --git a/src/backend/datasources/filters/AsciiFilter.cpp b/src/backend/datasources/filters/AsciiFilter.cpp
index bcb24b415..0115f7d10 100644
--- a/src/backend/datasources/filters/AsciiFilter.cpp
+++ b/src/backend/datasources/filters/AsciiFilter.cpp
@@ -1,1639 +1,1641 @@
 /***************************************************************************
 File                 : AsciiFilter.cpp
 Project              : LabPlot
 Description          : ASCII I/O-filter
 --------------------------------------------------------------------
 Copyright            : (C) 2009-2018 Stefan Gerlach (stefan.gerlach@uni.kn)
 Copyright            : (C) 2009-2017 Alexander Semke (alexander.semke@web.de)
 
 ***************************************************************************/
 
 /***************************************************************************
 *                                                                         *
 *  This program is free software; you can redistribute it and/or modify   *
 *  it under the terms of the GNU General Public License as published by   *
 *  the Free Software Foundation; either version 2 of the License, or      *
 *  (at your option) any later version.                                    *
 *                                                                         *
 *  This program is distributed in the hope that it will be useful,        *
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of         *
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          *
 *  GNU General Public License for more details.                           *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the Free Software           *
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor,                    *
 *   Boston, MA  02110-1301  USA                                           *
 *                                                                         *
 ***************************************************************************/
 #include "backend/datasources/LiveDataSource.h"
 #include "backend/core/column/Column.h"
 #include "backend/core/Project.h"
 #include "backend/datasources/filters/AsciiFilter.h"
 #include "backend/datasources/filters/AsciiFilterPrivate.h"
 #include "backend/worksheet/plots/cartesian/CartesianPlot.h"
 #include "backend/worksheet/plots/cartesian/XYCurve.h"
 #include "backend/lib/macros.h"
 #include "backend/lib/trace.h"
 
 #include <QTextStream>
 #include <KLocalizedString>
 #include <KFilterDev>
 #include <QProcess>
 #include <QDateTime>
 
 /*!
 \class AsciiFilter
 \brief Manages the import/export of data organized as columns (vectors) from/to an ASCII-file.
 
 \ingroup datasources
 */
 AsciiFilter::AsciiFilter() : AbstractFileFilter(), d(new AsciiFilterPrivate(this)) {}
 
 AsciiFilter::~AsciiFilter() {}
 
 /*!
   reads the content of the device \c device.
 */
 void AsciiFilter::readDataFromDevice(QIODevice& device, AbstractDataSource* dataSource, AbstractFileFilter::ImportMode importMode, int lines) {
 	d->readDataFromDevice(device, dataSource, importMode, lines);
 }
 
 void AsciiFilter::readFromLiveDeviceNotFile(QIODevice &device, AbstractDataSource* dataSource) {
 	d->readFromLiveDevice(device, dataSource);
 }
 
 qint64 AsciiFilter::readFromLiveDevice(QIODevice& device, AbstractDataSource* dataSource, qint64 from) {
 	return d->readFromLiveDevice(device, dataSource, from);
 }
 
 /*!
   reads the content of the file \c fileName.
 */
 void AsciiFilter::readDataFromFile(const QString& fileName, AbstractDataSource* dataSource, AbstractFileFilter::ImportMode importMode) {
 	d->readDataFromFile(fileName, dataSource, importMode);
 }
 
 QVector<QStringList> AsciiFilter::preview(const QString& fileName, int lines) {
 	return d->preview(fileName, lines);
 }
 
 QVector<QStringList> AsciiFilter::preview(QIODevice &device) {
 	return d->preview(device);
 }
 
 /*!
   reads the content of the file \c fileName to the data source \c dataSource.
 */
 //void AsciiFilter::read(const QString& fileName, AbstractDataSource* dataSource, AbstractFileFilter::ImportMode importMode) {
 //	d->read(fileName, dataSource, importMode);
 //}
 
 
 /*!
 writes the content of the data source \c dataSource to the file \c fileName.
 */
 void AsciiFilter::write(const QString& fileName, AbstractDataSource* dataSource) {
 	d->write(fileName, dataSource);
 // 	emit()
 }
 
 /*!
   loads the predefined filter settings for \c filterName
 */
 void AsciiFilter::loadFilterSettings(const QString& filterName) {
 	Q_UNUSED(filterName);
 }
 
 /*!
   saves the current settings as a new filter with the name \c filterName
 */
 void AsciiFilter::saveFilterSettings(const QString& filterName) const {
 	Q_UNUSED(filterName);
 }
 
 /*!
   returns the list with the names of all saved
   (system wide or user defined) filter settings.
 */
 QStringList AsciiFilter::predefinedFilters() {
 	return QStringList();
 }
 
 /*!
   returns the list of all predefined separator characters.
 */
 QStringList AsciiFilter::separatorCharacters() {
 	return (QStringList() << "auto" << "TAB" << "SPACE" << "," << ";" << ":"
 	        << ",TAB" << ";TAB" << ":TAB" << ",SPACE" << ";SPACE" << ":SPACE" << "2xSPACE" << "3xSPACE" << "4xSPACE" << "2xTAB");
 }
 
 /*!
 returns the list of all predefined comment characters.
 */
 QStringList AsciiFilter::commentCharacters() {
 	return (QStringList() << "#" << "!" << "//" << "+" << "c" << ":" << ";");
 }
 
 /*!
 returns the list of all predefined data types.
 */
 QStringList AsciiFilter::dataTypes() {
 	const QMetaObject& mo = AbstractColumn::staticMetaObject;
 	const QMetaEnum& me = mo.enumerator(mo.indexOfEnumerator("ColumnMode"));
 	QStringList list;
 	for (int i = 0; i <= 100; ++i)	// me.keyCount() does not work because we have holes in enum
 		if (me.valueToKey(i))
 			list << me.valueToKey(i);
 	return list;
 }
 
 QString AsciiFilter::fileInfoString(const QString& fileName) {
 	QString info(i18n("Number of columns: %1", AsciiFilter::columnNumber(fileName)));
 	info += QLatin1String("<br>");
 	info += i18n("Number of lines: %1", AsciiFilter::lineNumber(fileName));
 	return info;
 }
 
 /*!
     returns the number of columns in the file \c fileName.
 */
 int AsciiFilter::columnNumber(const QString& fileName, const QString& separator) {
 	KFilterDev device(fileName);
 	if (!device.open(QIODevice::ReadOnly)) {
 		DEBUG("Could not open file " << fileName.toStdString() << " for determining number of columns");
 		return -1;
 	}
 
 	QString line = device.readLine();
 	line.remove(QRegExp("[\\n\\r]"));
 
 	QStringList lineStringList;
 	if (separator.length() > 0)
 		lineStringList = line.split(separator);
 	else
 		lineStringList = line.split(QRegExp("\\s+"));
 	DEBUG("number of columns : " << lineStringList.size());
 
 	return lineStringList.size();
 }
 
 size_t AsciiFilter::lineNumber(const QString& fileName) {
 	KFilterDev device(fileName);
 	if (!device.open(QIODevice::ReadOnly)) {
 		DEBUG("Could not open file " << fileName.toStdString() << " to determine number of lines");
 		return 0;
 	}
 	if (!device.canReadLine())
 		return -1;
 
 	size_t lineCount = 0;
 	while (!device.atEnd()) {
 		device.readLine();
 		lineCount++;
 	}
 
 //TODO: wc is much faster but not portable
 	/*	QElapsedTimer myTimer;
 		myTimer.start();
 		QProcess wc;
 		wc.start(QString("wc"), QStringList() << "-l" << fileName);
 		size_t lineCount = 0;
 		while (wc.waitForReadyRead())
 			lineCount = wc.readLine().split(' ')[0].toInt();
 		lineCount++;	// last line not counted
 		DEBUG(" Elapsed time counting lines : " << myTimer.elapsed() << " ms");
 	*/
 	return lineCount;
 }
 
 /*!
   returns the number of lines in the device \c device and 0 if sequential.
   resets the position to 0!
 */
 size_t AsciiFilter::lineNumber(QIODevice &device) {
 	if (device.isSequential())
 		return 0;
 	if (!device.canReadLine())
 		DEBUG("WARNING in AsciiFilter::lineNumber(): device cannot 'readLine()' but using it anyway.");
 
 	size_t lineCount = 0;
 	device.seek(0);
 	while (!device.atEnd()) {
 		device.readLine();
 		lineCount++;
 	}
 	device.seek(0);
 
 	return lineCount;
 }
 
 void AsciiFilter::setCommentCharacter(const QString& s) {
 	d->commentCharacter = s;
 }
 QString AsciiFilter::commentCharacter() const {
 	return d->commentCharacter;
 }
 
 void AsciiFilter::setSeparatingCharacter(const QString& s) {
 	d->separatingCharacter = s;
 }
 QString AsciiFilter::separatingCharacter() const {
 	return d->separatingCharacter;
 }
 
 void AsciiFilter::setDateTimeFormat(const QString &f) {
 	d->dateTimeFormat = f;
 }
 QString AsciiFilter::dateTimeFormat() const {
 	return d->dateTimeFormat;
 }
 
 void AsciiFilter::setNumberFormat(QLocale::Language lang) {
 	d->numberFormat = lang;
 }
 QLocale::Language AsciiFilter::numberFormat() const {
 	return d->numberFormat;
 }
 
 void AsciiFilter::setAutoModeEnabled(const bool b) {
 	d->autoModeEnabled = b;
 }
 bool AsciiFilter::isAutoModeEnabled() const {
 	return d->autoModeEnabled;
 }
 
 void AsciiFilter::setHeaderEnabled(const bool b) {
 	d->headerEnabled = b;
 }
 bool AsciiFilter::isHeaderEnabled() const {
 	return d->headerEnabled;
 }
 
 void AsciiFilter::setSkipEmptyParts(const bool b) {
 	d->skipEmptyParts = b;
 }
 bool AsciiFilter::skipEmptyParts() const {
 	return d->skipEmptyParts;
 }
 
 void AsciiFilter::setCreateIndexEnabled(bool b) {
 	d->createIndexEnabled = b;
 }
 
 void AsciiFilter::setSimplifyWhitespacesEnabled(bool b) {
 	d->simplifyWhitespacesEnabled = b;
 }
 bool AsciiFilter::simplifyWhitespacesEnabled() const {
 	return d->simplifyWhitespacesEnabled;
 }
 
 void AsciiFilter::setNaNValueToZero(bool b) {
 	if (b)
 		d->nanValue = 0;
 	else
 		d->nanValue = NAN;
 }
 bool AsciiFilter::NaNValueToZeroEnabled() const {
 	if (d->nanValue == 0)
 		return true;
 	return false;
 }
 
 void AsciiFilter::setRemoveQuotesEnabled(bool b) {
 	d->removeQuotesEnabled = b;
 }
 bool AsciiFilter::removeQuotesEnabled() const {
 	return d->removeQuotesEnabled;
 }
 
 void AsciiFilter::setVectorNames(const QString& s) {
 	d->vectorNames.clear();
 	if (!s.simplified().isEmpty())
 		d->vectorNames = s.simplified().split(' ');
 }
 QStringList AsciiFilter::vectorNames() const {
 	return d->vectorNames;
 }
 
 QVector<AbstractColumn::ColumnMode> AsciiFilter::columnModes() {
 	return d->columnModes;
 }
 
 void AsciiFilter::setStartRow(const int r) {
 	d->startRow = r;
 }
 int AsciiFilter::startRow() const {
 	return d->startRow;
 }
 
 void AsciiFilter::setEndRow(const int r) {
 	d->endRow = r;
 }
 int AsciiFilter::endRow() const {
 	return d->endRow;
 }
 
 void AsciiFilter::setStartColumn(const int c) {
 	d->startColumn = c;
 }
 int AsciiFilter::startColumn() const {
 	return d->startColumn;
 }
 
 void AsciiFilter::setEndColumn(const int c) {
 	d->endColumn = c;
 }
 int AsciiFilter::endColumn() const {
 	return d->endColumn;
 }
 
 //#####################################################################
 //################### Private implementation ##########################
 //#####################################################################
 AsciiFilterPrivate::AsciiFilterPrivate(AsciiFilter* owner) : q(owner),
 	commentCharacter("#"),
 	separatingCharacter("auto"),
 	numberFormat(QLocale::C),
 	autoModeEnabled(true),
 	headerEnabled(true),
 	skipEmptyParts(false),
 	simplifyWhitespacesEnabled(true),
 	nanValue(NAN),
 	removeQuotesEnabled(false),
 	createIndexEnabled(false),
 	startRow(1),
 	endRow(-1),
 	startColumn(1),
 	endColumn(-1),
 	m_actualStartRow(1),
 	m_actualRows(0),
 	m_actualCols(0),
 	m_prepared(false),
 	m_columnOffset(0) {
 }
 
 /*!
  * get a single line from device
  */
 QStringList AsciiFilterPrivate::getLineString(QIODevice& device) {
 	QString line;
 	do {	// skip comment lines in data lines
 		if (!device.canReadLine())
 			DEBUG("WARNING in AsciiFilterPrivate::getLineString(): device cannot 'readLine()' but using it anyway.");
 //			line = device.readAll();
 		line = device.readLine();
 	} while (line.startsWith(commentCharacter));
 
 	line.remove(QRegExp("[\\n\\r]"));	// remove any newline
 	if (simplifyWhitespacesEnabled)
 		line = line.simplified();
 	DEBUG("data line : \'" << line.toStdString() << '\'');
 	QStringList lineStringList = line.split(m_separator, (QString::SplitBehavior)skipEmptyParts);
 	//TODO: remove quotes here?
 	QDEBUG("data line, parsed: " << lineStringList);
 
 	return lineStringList;
 }
 
 /*!
  * returns -1 if the device couldn't be opened, 1 if the current read position in the device is at the end and 0 otherwise.
  */
 int AsciiFilterPrivate::prepareDeviceToRead(QIODevice& device) {
 	DEBUG("AsciiFilterPrivate::prepareDeviceToRead(): is sequential = " << device.isSequential() << ", can readLine = " << device.canReadLine());
 
 	if (!device.open(QIODevice::ReadOnly))
 		return -1;
 
 	if (device.atEnd() && !device.isSequential()) // empty file
 		return 1;
 
 /////////////////////////////////////////////////////////////////
 	// Find first data line (ignoring comment lines)
 	DEBUG("	Skipping " << startRow - 1 << " lines");
 	for (int i = 0; i < startRow - 1; ++i) {
 		QString line;
 		if (!device.canReadLine())
 			DEBUG("WARNING in AsciiFilterPrivate::prepareDeviceToRead(): device cannot 'readLine()' but using it anyway.");
 		line = device.readLine();
 		DEBUG("	line = " << line.toStdString());
 
 		if (device.atEnd()) {
 			if (device.isSequential())
 				break;
 			else
 				return 1;
 		}
 
-		//TOOD: this logic seems to be wrong. If the user asks to read from line startRow, we should start here independent of any comments
+		//TODO: this logic seems to be wrong. If the user asks to read from line startRow, we should start here independent of any comments
 		if (line.startsWith(commentCharacter))	// ignore commented lines before startRow
 			i--;
 	}
 
 	// Parse the first line:
 	// Determine the number of columns, create the columns and use (if selected) the first row to name them
 	QString firstLine;
 	do {	// skip comment lines
 		if (!device.canReadLine())
 			DEBUG("WARNING in AsciiFilterPrivate::prepareDeviceToRead(): device cannot 'readLine()' but using it anyway.");
 
 		firstLine = device.readLine();
 
 		if (device.atEnd()) {
 			if (device.isSequential())
 				break;
 			else
 				return 1;
 		}
 	} while (firstLine.startsWith(commentCharacter));
 
 	DEBUG(" device position after first line and comments = " << device.pos());
 	firstLine.remove(QRegExp("[\\n\\r]"));	// remove any newline
 	if (simplifyWhitespacesEnabled)
 		firstLine = firstLine.simplified();
 	DEBUG("First line: \'" << firstLine.toStdString() << '\'');
 
 	// determine separator and split first line
 	QStringList firstLineStringList;
 	if (separatingCharacter == "auto") {
 		DEBUG("automatic separator");
 		QRegExp regExp("(\\s+)|(,\\s+)|(;\\s+)|(:\\s+)");
 		firstLineStringList = firstLine.split(regExp, (QString::SplitBehavior)skipEmptyParts);
 
 		if (!firstLineStringList.isEmpty()) {
 			int length1 = firstLineStringList.at(0).length();
 			if (firstLineStringList.size() > 1) {
 				int pos2 = firstLine.indexOf(firstLineStringList.at(1), length1);
 				m_separator = firstLine.mid(length1, pos2 - length1);
 			} else {
 				//old: separator = line.right(line.length() - length1);
 				m_separator = ' ';
 			}
 		}
 	} else {	// use given separator
 		// replace symbolic "TAB" with '\t'
 		m_separator = separatingCharacter.replace(QLatin1String("2xTAB"), "\t\t", Qt::CaseInsensitive);
 		m_separator = separatingCharacter.replace(QLatin1String("TAB"), "\t", Qt::CaseInsensitive);
 		// replace symbolic "SPACE" with ' '
 		m_separator = m_separator.replace(QLatin1String("2xSPACE"), QLatin1String("  "), Qt::CaseInsensitive);
 		m_separator = m_separator.replace(QLatin1String("3xSPACE"), QLatin1String("   "), Qt::CaseInsensitive);
 		m_separator = m_separator.replace(QLatin1String("4xSPACE"), QLatin1String("    "), Qt::CaseInsensitive);
 		m_separator = m_separator.replace(QLatin1String("SPACE"), QLatin1String(" "), Qt::CaseInsensitive);
 		firstLineStringList = firstLine.split(m_separator, (QString::SplitBehavior)skipEmptyParts);
 	}
 	DEBUG("separator: \'" << m_separator.toStdString() << '\'');
 	DEBUG("number of columns: " << firstLineStringList.size());
 	QDEBUG("first line: " << firstLineStringList);
 	DEBUG("headerEnabled: " << headerEnabled);
 
 	//optionally, remove potential spaces in the first line
 	if (simplifyWhitespacesEnabled) {
 		for (int i = 0; i < firstLineStringList.size(); ++i)
 			firstLineStringList[i] = firstLineStringList[i].simplified();
 	}
 
 	if (headerEnabled) {	// use first line to name vectors
 		vectorNames = firstLineStringList;
 		QDEBUG("vector names =" << vectorNames);
 		m_actualStartRow = startRow + 1;
 	} else
 		m_actualStartRow = startRow;
 
 	// set range to read
 	if (endColumn == -1) {
 		if (headerEnabled || vectorNames.size() == 0)
 			endColumn = firstLineStringList.size(); // last column
 		else
 			//number of vector names provided in the import dialog (not more than the maximal number of columns in the file)
 			endColumn = qMin(vectorNames.size(), firstLineStringList.size());
 	}
 	if (createIndexEnabled) {
 		vectorNames.prepend(i18n("Index"));
 		endColumn++;
 	}
 	m_actualCols = endColumn - startColumn + 1;
 
 //TEST: readline-seek-readline fails
 	/*	qint64 testpos = device.pos();
 		DEBUG("read data line @ pos " << testpos << " : " << device.readLine().toStdString());
 		device.seek(testpos);
 		testpos = device.pos();
 		DEBUG("read data line again @ pos " << testpos << "  : " << device.readLine().toStdString());
 	*/
 /////////////////////////////////////////////////////////////////
 
 	// parse first data line to determine data type for each column
 	if (!device.isSequential())
 		firstLineStringList = getLineString(device);
 
 	columnModes.resize(m_actualCols);
 	int col = 0;
 	if (createIndexEnabled) {
 		columnModes[0] = AbstractColumn::Integer;
 		col = 1;
 	}
 
 	for (auto& valueString: firstLineStringList) { // parse columns available in first data line
 		if (simplifyWhitespacesEnabled)
 			valueString = valueString.simplified();
 		if (col == m_actualCols)
 			break;
 		columnModes[col++] = AbstractFileFilter::columnMode(valueString, dateTimeFormat, numberFormat);
 	}
 	// parsing more lines to better determine data types
 	for (unsigned int i = 0; i < m_dataTypeLines; ++i) {
+		if (device.atEnd())	// EOF reached
+			break;
 		firstLineStringList = getLineString(device);
 
 		if (createIndexEnabled)
 			col = 1;
 		else
 			col = 0;
 		for (auto& valueString: firstLineStringList) {
 			if (simplifyWhitespacesEnabled)
 				valueString = valueString.simplified();
 			if (col == m_actualCols)
 				break;
 			AbstractColumn::ColumnMode mode = AbstractFileFilter::columnMode(valueString, dateTimeFormat, numberFormat);
 
 			// numeric: integer -> numeric
 			if (mode == AbstractColumn::Numeric && columnModes[col] == AbstractColumn::Integer)
 				columnModes[col] = mode;
 			// text: non text -> text
 			if (mode == AbstractColumn::Text && columnModes[col] != AbstractColumn::Text)
 				columnModes[col] = mode;
 
 			col++;
 		}
 	}
 	QDEBUG("column modes = " << columnModes);
 
 	// ATTENTION: This resets the position in the device to 0
 	m_actualRows = (int)AsciiFilter::lineNumber(device);
 
 	const int actualEndRow = (endRow == -1 || endRow > m_actualRows) ? m_actualRows : endRow;
 	m_actualRows = actualEndRow - m_actualStartRow + 1;
 
 	DEBUG("start/end column: " << startColumn << ' ' << endColumn);
 	DEBUG("start/end row: " << m_actualStartRow << ' ' << actualEndRow);
 	DEBUG("actual cols/rows (w/o header): " << m_actualCols << ' ' << m_actualRows);
 
 	if (m_actualRows == 0 && !device.isSequential())
 		return 1;
 
 	return 0;
 }
 
 /*!
     reads the content of the file \c fileName to the data source \c dataSource. Uses the settings defined in the data source.
 */
 void AsciiFilterPrivate::readDataFromFile(const QString& fileName, AbstractDataSource* dataSource, AbstractFileFilter::ImportMode importMode) {
 	DEBUG("AsciiFilterPrivate::readDataFromFile(): fileName = \'" << fileName.toStdString() << "\', dataSource = "
 	      << dataSource << ", mode = " << ENUM_TO_STRING(AbstractFileFilter, ImportMode, importMode));
 
 	KFilterDev device(fileName);
 	readDataFromDevice(device, dataSource, importMode);
 }
 
 qint64 AsciiFilterPrivate::readFromLiveDevice(QIODevice& device, AbstractDataSource* dataSource, qint64 from) {
 	DEBUG("AsciiFilterPrivate::readFromLiveDevice(): bytes available = " << device.bytesAvailable() << ", from = " << from);
 	if (!(device.bytesAvailable() > 0)) {
 		DEBUG("	No new data available");
 		return 0;
 	}
 
 	LiveDataSource* spreadsheet = dynamic_cast<LiveDataSource*>(dataSource);
 
 	if (spreadsheet->sourceType() != LiveDataSource::SourceType::FileOrPipe)
 		if (device.isSequential() && device.bytesAvailable() < (int)sizeof(quint16))
 			return 0;
 
 	if (!m_prepared) {
 		DEBUG("Preparing ..");
 
 		switch (spreadsheet->sourceType()) {
 		case LiveDataSource::SourceType::FileOrPipe: {
 			const int deviceError = prepareDeviceToRead(device);
 			if (deviceError != 0) {
 				DEBUG("Device error = " << deviceError);
 				return 0;
 			}
 			break;
 		}
 		case LiveDataSource::SourceType::NetworkTcpSocket:
 		case LiveDataSource::SourceType::NetworkUdpSocket:
 		case LiveDataSource::SourceType::LocalSocket:
 		case LiveDataSource::SourceType::SerialPort:
 			m_actualRows = 1;
 			if (createIndexEnabled) {
 				m_actualCols = 2;
 				columnModes << AbstractColumn::Integer << AbstractColumn::Numeric;
 				vectorNames << i18n("Index") << i18n("Value");
 			} else {
 				m_actualCols = 1;
 				columnModes << AbstractColumn::Numeric;
 				vectorNames << i18n("Value");
 			}
 			QDEBUG("	vector names = " << vectorNames);
 		}
 
 		// prepare import for spreadsheet
 		spreadsheet->setUndoAware(false);
 		spreadsheet->resize(AbstractFileFilter::Replace, vectorNames, m_actualCols);
 		DEBUG("	data source resized to col: " << m_actualCols);
 		DEBUG("	data source rowCount: " << spreadsheet->rowCount());
 
 		//columns in a file data source don't have any manual changes.
 		//make the available columns undo unaware and suppress the "data changed" signal.
 		//data changes will be propagated via an explicit Column::setChanged() call once new data was read.
 		for (int i = 0; i < spreadsheet->childCount<Column>(); i++) {
 			spreadsheet->child<Column>(i)->setUndoAware(false);
 			spreadsheet->child<Column>(i)->setSuppressDataChangedSignal(true);
 		}
 
 		int keepNValues = spreadsheet->keepNValues();
 		if (keepNValues == 0)
 			spreadsheet->setRowCount(m_actualRows > 1 ? m_actualRows : 1);
 		else {
 			spreadsheet->setRowCount(keepNValues);
 			m_actualRows = keepNValues;
 		}
 
 		m_dataContainer.resize(m_actualCols);
 
 		DEBUG("	Setting data ..");
 		for (int n = 0; n < m_actualCols; ++n) {
 			// data() returns a void* which is a pointer to any data type (see ColumnPrivate.cpp)
 			spreadsheet->child<Column>(n)->setColumnMode(columnModes[n]);
 			switch (columnModes[n]) {
 			case AbstractColumn::Numeric: {
 				QVector<double>* vector = static_cast<QVector<double>* >(spreadsheet->child<Column>(n)->data());
 				vector->resize(m_actualRows);
 				m_dataContainer[n] = static_cast<void *>(vector);
 				break;
 			}
 			case AbstractColumn::Integer: {
 				QVector<int>* vector = static_cast<QVector<int>* >(spreadsheet->child<Column>(n)->data());
 				vector->resize(m_actualRows);
 				m_dataContainer[n] = static_cast<void *>(vector);
 				break;
 			}
 			case AbstractColumn::Text: {
 				QVector<QString>* vector = static_cast<QVector<QString>*>(spreadsheet->child<Column>(n)->data());
 				vector->resize(m_actualRows);
 				m_dataContainer[n] = static_cast<void *>(vector);
 				break;
 			}
 			case AbstractColumn::DateTime: {
 				QVector<QDateTime>* vector = static_cast<QVector<QDateTime>* >(spreadsheet->child<Column>(n)->data());
 				vector->resize(m_actualRows);
 				m_dataContainer[n] = static_cast<void *>(vector);
 				break;
 			}
 			//TODO
 			case AbstractColumn::Month:
 			case AbstractColumn::Day:
 				break;
 			}
 		}
 
 		DEBUG("Prepared!");
 	}
 
 	qint64 bytesread = 0;
 
 #ifdef PERFTRACE_LIVE_IMPORT
 	PERFTRACE("AsciiLiveDataImportTotal: ");
 #endif
 	LiveDataSource::ReadingType readingType;
 	if (!m_prepared) {
 		readingType = LiveDataSource::ReadingType::TillEnd;
 	} else {
 		//we have to read all the data when reading from end
 		//so we set readingType to TillEnd
 		if (spreadsheet->readingType() == LiveDataSource::ReadingType::FromEnd)
 			readingType = LiveDataSource::ReadingType::TillEnd;
 		//if we read the whole file we just start from the beginning of it
 		//and read till end
 		else if (spreadsheet->readingType() == LiveDataSource::ReadingType::WholeFile)
 			readingType = LiveDataSource::ReadingType::TillEnd;
 		else
 			readingType = spreadsheet->readingType();
 	}
 	DEBUG("	reading type = " << ENUM_TO_STRING(LiveDataSource, ReadingType, readingType));
 
 	//move to the last read position, from == total bytes read
 	//since the other source types are sequencial we cannot seek on them
 	if (spreadsheet->sourceType() == LiveDataSource::SourceType::FileOrPipe)
 		device.seek(from);
 	DEBUG("	bytes available = " << device.bytesAvailable());
 
 	//count the new lines, increase actualrows on each
 	//now we read all the new lines, if we want to use sample rate
 	//then here we can do it, if we have actually sample rate number of lines :-?
 	int newLinesForSampleSizeNotTillEnd = 0;
 	int newLinesTillEnd = 0;
 	QVector<QString> newData;
 	if (readingType != LiveDataSource::ReadingType::TillEnd)
 		newData.resize(spreadsheet->sampleSize());
 
 	int newDataIdx = 0;
 	{
 #ifdef PERFTRACE_LIVE_IMPORT
 		PERFTRACE("AsciiLiveDataImportReadingFromFile: ");
 #endif
 		while (!device.atEnd()) {
 			DEBUG("	reading type = " << ENUM_TO_STRING(LiveDataSource, ReadingType, readingType));
 			DEBUG("	source type = " << ENUM_TO_STRING(LiveDataSource, SourceType, spreadsheet->sourceType()));
 			if (readingType != LiveDataSource::ReadingType::TillEnd) {
 				switch (spreadsheet->sourceType()) {	// different sources need different read methods
 				case LiveDataSource::SourceType::LocalSocket:
 					newData[newDataIdx++] = device.readAll();
 					break;
 				case LiveDataSource::SourceType::NetworkUdpSocket:
 					newData[newDataIdx++] = device.read(device.bytesAvailable());
 					break;
 				case LiveDataSource::SourceType::FileOrPipe:
 				case LiveDataSource::SourceType::NetworkTcpSocket:
 				//TODO: check serial port
 				case LiveDataSource::SourceType::SerialPort:
 					if (!device.canReadLine())
 						DEBUG("WARNING in AsciiFilterPrivate::readFromLiveDevice(): device cannot 'readLine()' but using it anyway.");
 					newData[newDataIdx++] = device.readLine();
 				}
 			} else {	// ReadingType::TillEnd
 				switch (spreadsheet->sourceType()) {	// different sources need different read methods
 				case LiveDataSource::SourceType::LocalSocket:
 					newData.push_back(device.readAll());
 					break;
 				case LiveDataSource::SourceType::NetworkUdpSocket:
 					newData.push_back(device.read(device.bytesAvailable()));
 					break;
 				case LiveDataSource::SourceType::FileOrPipe:
 				case LiveDataSource::SourceType::NetworkTcpSocket:
 				//TODO: check serial port
 				case LiveDataSource::SourceType::SerialPort:
 					if (!device.canReadLine())
 						DEBUG("WARNING in AsciiFilterPrivate::readFromLiveDevice(): device cannot 'readLine()' but using it anyway.");
 					newData.push_back(device.readLine());
 				}
 			}
 			newLinesTillEnd++;
 
 			if (readingType != LiveDataSource::ReadingType::TillEnd) {
 				newLinesForSampleSizeNotTillEnd++;
 				//for Continuous reading and FromEnd we read sample rate number of lines if possible
 				//here TillEnd and Whole file behave the same
 				if (newLinesForSampleSizeNotTillEnd == spreadsheet->sampleSize())
 					break;
 			}
 		}
 		QDEBUG("	data read: " << newData);
 	}
 	//now we reset the readingType
 	if (spreadsheet->readingType() == LiveDataSource::ReadingType::FromEnd)
 		readingType = spreadsheet->readingType();
 
 	//we had less new lines than the sample size specified
 	if (readingType != LiveDataSource::ReadingType::TillEnd)
 		QDEBUG("Removed empty lines: " << newData.removeAll(""));
 
 	//back to the last read position before counting when reading from files
 	if (spreadsheet->sourceType() == LiveDataSource::SourceType::FileOrPipe)
 		device.seek(from);
 
 	const int spreadsheetRowCountBeforeResize = spreadsheet->rowCount();
 
 	int currentRow = 0; // indexes the position in the vector(column)
 	int linesToRead = 0;
 	int keepNValues = spreadsheet->keepNValues();
 
 	DEBUG("Increase row count");
 	if (m_prepared) {
 		//increase row count if we don't have a fixed size
 		//but only after the preparation step
 		if (keepNValues == 0) {
 			if (readingType != LiveDataSource::ReadingType::TillEnd)
 				m_actualRows += qMin(newData.size(), spreadsheet->sampleSize());
 			else {
 				//we don't increase it if we reread the whole file, we reset it
 				if (!(spreadsheet->readingType() == LiveDataSource::ReadingType::WholeFile))
 					m_actualRows += newData.size();
 				else
 					m_actualRows = newData.size();
 			}
 
 			//appending
 			if (spreadsheet->readingType() == LiveDataSource::ReadingType::WholeFile)
 				linesToRead = m_actualRows;
 			else
 				linesToRead = m_actualRows - spreadsheetRowCountBeforeResize;
 		} else {	// fixed size
 			if (readingType == LiveDataSource::ReadingType::TillEnd) {
 				//we had more lines than the fixed size, so we read m_actualRows number of lines
 				if (newLinesTillEnd > m_actualRows) {
 					linesToRead = m_actualRows;
 					//TODO after reading we should skip the next data lines
 					//because it's TillEnd actually
 				} else
 					linesToRead = newLinesTillEnd;
 			} else {
 				//we read max sample rate number of lines when the reading mode
 				//is ContinuouslyFixed or FromEnd, WholeFile is disabled
 				linesToRead = qMin(spreadsheet->sampleSize(), newLinesTillEnd);
 			}
 		}
 		DEBUG("	actual rows = " << m_actualRows);
 
 		if (linesToRead == 0)
 			return 0;
 	} else {
 		linesToRead = newLinesTillEnd;
 		if (headerEnabled)
 			--m_actualRows;
 	}
 	DEBUG("	lines to read = " << linesToRead);
 
 	//TODO: check other source types
 	if (spreadsheet->sourceType() == LiveDataSource::SourceType::NetworkUdpSocket) {
 		if (m_actualRows < linesToRead) {
 			DEBUG("	SET actual rows to " << linesToRead);
 			m_actualRows = linesToRead;
 		}
 	}
 
 	//new rows/resize columns if we don't have a fixed size
 	//TODO if the user changes this value..m_resizedToFixedSize..setResizedToFixedSize
 	if (keepNValues == 0) {
 #ifdef PERFTRACE_LIVE_IMPORT
 		PERFTRACE("AsciiLiveDataImportResizing: ");
 #endif
 		if (spreadsheet->rowCount() < m_actualRows)
 			spreadsheet->setRowCount(m_actualRows);
 
 		if (!m_prepared)
 			currentRow = 0;
 		else {
 			// indexes the position in the vector(column)
 			if (spreadsheet->readingType() == LiveDataSource::ReadingType::WholeFile)
 				currentRow = 0;
 			else
 				currentRow = spreadsheetRowCountBeforeResize;
 		}
 
 		// if we have fixed size, we do this only once in preparation, here we can use
 		// m_prepared and we need something to decide whether it has a fixed size or increasing
 		for (int n = 0; n < m_actualCols; ++n) {
 			// data() returns a void* which is a pointer to any data type (see ColumnPrivate.cpp)
 			switch (columnModes[n]) {
 			case AbstractColumn::Numeric: {
 				QVector<double>* vector = static_cast<QVector<double>* >(spreadsheet->child<Column>(n)->data());
 				vector->resize(m_actualRows);
 				m_dataContainer[n] = static_cast<void *>(vector);
 				break;
 			}
 			case AbstractColumn::Integer: {
 				QVector<int>* vector = static_cast<QVector<int>* >(spreadsheet->child<Column>(n)->data());
 				vector->resize(m_actualRows);
 				m_dataContainer[n] = static_cast<void *>(vector);
 				break;
 			}
 			case AbstractColumn::Text: {
 				QVector<QString>* vector = static_cast<QVector<QString>*>(spreadsheet->child<Column>(n)->data());
 				vector->resize(m_actualRows);
 				m_dataContainer[n] = static_cast<void *>(vector);
 				break;
 			}
 			case AbstractColumn::DateTime: {
 				QVector<QDateTime>* vector = static_cast<QVector<QDateTime>* >(spreadsheet->child<Column>(n)->data());
 				vector->resize(m_actualRows);
 				m_dataContainer[n] = static_cast<void *>(vector);
 				break;
 			}
 			//TODO
 			case AbstractColumn::Month:
 			case AbstractColumn::Day:
 				break;
 			}
 		}
 	} else {
 		//when we have a fixed size we have to pop sampleSize number of lines if specified
 		//here popping, setting currentRow
 		if (!m_prepared) {
 			if (spreadsheet->readingType() == LiveDataSource::ReadingType::WholeFile)
 				currentRow = 0;
 			else
 				currentRow = m_actualRows - qMin(newLinesTillEnd, m_actualRows);
 		} else {
 			if (readingType == LiveDataSource::ReadingType::TillEnd) {
 				if (newLinesTillEnd > m_actualRows) {
 					currentRow = 0;
 				} else {
 					if (spreadsheet->readingType() == LiveDataSource::ReadingType::WholeFile)
 						currentRow = 0;
 					else
 						currentRow = m_actualRows - newLinesTillEnd;
 				}
 			} else {
 				//we read max sample rate number of lines when the reading mode
 				//is ContinuouslyFixed or FromEnd
 				currentRow = m_actualRows - qMin(spreadsheet->sampleSize(), newLinesTillEnd);
 			}
 		}
 
 		if (m_prepared) {
 #ifdef PERFTRACE_LIVE_IMPORT
 			PERFTRACE("AsciiLiveDataImportPopping: ");
 #endif
 			for (int row = 0; row < linesToRead; ++row) {
 				for (int col = 0; col < m_actualCols; ++col) {
 					switch (columnModes[col]) {
 					case AbstractColumn::Numeric: {
 						QVector<double>* vector = static_cast<QVector<double>* >(spreadsheet->child<Column>(col)->data());
 						vector->pop_front();
 						vector->resize(m_actualRows);
 						m_dataContainer[col] = static_cast<void *>(vector);
 						break;
 					}
 					case AbstractColumn::Integer: {
 						QVector<int>* vector = static_cast<QVector<int>* >(spreadsheet->child<Column>(col)->data());
 						vector->pop_front();
 						vector->resize(m_actualRows);
 						m_dataContainer[col] = static_cast<void *>(vector);
 						break;
 					}
 					case AbstractColumn::Text: {
 						QVector<QString>* vector = static_cast<QVector<QString>*>(spreadsheet->child<Column>(col)->data());
 						vector->pop_front();
 						vector->resize(m_actualRows);
 						m_dataContainer[col] = static_cast<void *>(vector);
 						break;
 					}
 					case AbstractColumn::DateTime: {
 						QVector<QDateTime>* vector = static_cast<QVector<QDateTime>* >(spreadsheet->child<Column>(col)->data());
 						vector->pop_front();
 						vector->resize(m_actualRows);
 						m_dataContainer[col] = static_cast<void *>(vector);
 						break;
 					}
 					//TODO
 					case AbstractColumn::Month:
 					case AbstractColumn::Day:
 						break;
 					}
 				}
 			}
 		}
 	}
 
 	// from the last row we read the new data in the spreadsheet
 	qDebug() << "reading from line"  << currentRow << " till end" << newLinesTillEnd;
 	qDebug() << "Lines to read:" << linesToRead <<", actual rows:" << m_actualRows << ", actual cols:" << m_actualCols;
 	newDataIdx = 0;
 	if (readingType == LiveDataSource::ReadingType::FromEnd) {
 		if (m_prepared) {
 			if (newData.size() > spreadsheet->sampleSize())
 				newDataIdx = newData.size() - spreadsheet->sampleSize();
 			//since we skip a couple of lines, we need to count those bytes too
 			for (int i = 0; i < newDataIdx; ++i)
 				bytesread += newData.at(i).size();
 		}
 	}
 	qDebug() << "newDataIdx: " << newDataIdx;
 	//TODO
 	static int indexColumnIdx = 0;
 	{
 #ifdef PERFTRACE_LIVE_IMPORT
 		PERFTRACE("AsciiLiveDataImportFillingContainers: ");
 #endif
 		int row = 0;
 
 		if (readingType == LiveDataSource::ReadingType::TillEnd || (readingType == LiveDataSource::ReadingType::ContinuousFixed)) {
 			if (headerEnabled) {
 				if (!m_prepared) {
 					row = 1;
 					bytesread += newData.at(0).size();
 				}
 			}
 		}
 		if (spreadsheet->sourceType() == LiveDataSource::SourceType::FileOrPipe) {
 			if (readingType == LiveDataSource::ReadingType::WholeFile) {
 				if (headerEnabled) {
 					row = 1;
 					bytesread += newData.at(0).size();
 				}
 			}
 		}
 
 		for (; row < linesToRead; ++row) {
 			DEBUG("	row = " << row);
 			QString line;
 			if (readingType == LiveDataSource::ReadingType::FromEnd)
 				line = newData.at(newDataIdx++);
 			else
 				line = newData.at(row);
 			//when we read the whole file we don't care about the previous position
 			//so we don't have to count those bytes
 			if (readingType != LiveDataSource::ReadingType::WholeFile) {
 				if (spreadsheet->sourceType() == LiveDataSource::SourceType::FileOrPipe) {
 					bytesread += line.size();
 				}
 			}
 
 			//qDebug() << "line bytes: " << line.size() << " line: " << line;
 			if (simplifyWhitespacesEnabled)
 				line = line.simplified();
 
 			if (line.isEmpty() || line.startsWith(commentCharacter)) // skip empty or commented lines
 				continue;
 
 			QLocale locale(numberFormat);
 
 			QStringList lineStringList;
 			// only FileOrPipe support multiple columns
 			if (spreadsheet->sourceType() == LiveDataSource::SourceType::FileOrPipe)
 				lineStringList = line.split(m_separator, (QString::SplitBehavior)skipEmptyParts);
 			else
 				lineStringList << line;
 			QDEBUG(" line = " << lineStringList << ", separator = \'" << m_separator << "\'");
 
 			if (createIndexEnabled) {
 				if (spreadsheet->keepNValues() == 0)
 					lineStringList.prepend(QString::number(currentRow));
 				else
 					lineStringList.prepend(QString::number(indexColumnIdx++));
 			}
 
 			QDEBUG("	column modes = " << columnModes);
 			for (int n = 0; n < m_actualCols; ++n) {
 				DEBUG("	actual col = " << n);
 				if (n < lineStringList.size()) {
 					QString valueString = lineStringList.at(n);
 					DEBUG("	value string = " << valueString.toStdString());
 
 					// set value depending on data type
 					switch (columnModes[n]) {
 					case AbstractColumn::Numeric: {
 						DEBUG("	Numeric");
 						bool isNumber;
 						const double value = locale.toDouble(valueString, &isNumber);
 						static_cast<QVector<double>*>(m_dataContainer[n])->operator[](currentRow) = (isNumber ? value : nanValue);
 						qDebug() << "dataContainer[" << n << "] size:" << static_cast<QVector<double>*>(m_dataContainer[n])->size();
 						break;
 					}
 					case AbstractColumn::Integer: {
 						DEBUG("	Integer");
 						bool isNumber;
 						const int value = locale.toInt(valueString, &isNumber);
 						DEBUG("	container size = " << m_dataContainer.size() << ", current row = " << currentRow);
 						static_cast<QVector<int>*>(m_dataContainer[n])->operator[](currentRow) = (isNumber ? value : 0);
 						qDebug() << "dataContainer[" << n << "] size:" << static_cast<QVector<int>*>(m_dataContainer[n])->size();
 
 						break;
 					}
 					case AbstractColumn::DateTime: {
 						const QDateTime valueDateTime = QDateTime::fromString(valueString, dateTimeFormat);
 						static_cast<QVector<QDateTime>*>(m_dataContainer[n])->operator[](currentRow) = valueDateTime.isValid() ? valueDateTime : QDateTime();
 						break;
 					}
 					case AbstractColumn::Text:
 						if (removeQuotesEnabled)
 							valueString.remove(QRegExp("[\"\']"));
 						static_cast<QVector<QString>*>(m_dataContainer[n])->operator[](currentRow) = valueString;
 						break;
 					case AbstractColumn::Month:
 						//TODO
 						break;
 					case AbstractColumn::Day:
 						//TODO
 						break;
 					}
 				} else {
 					DEBUG("	missing columns in this line");
 					switch (columnModes[n]) {
 					case AbstractColumn::Numeric:
 						static_cast<QVector<double>*>(m_dataContainer[n])->operator[](currentRow) = nanValue;
 						break;
 					case AbstractColumn::Integer:
 						static_cast<QVector<int>*>(m_dataContainer[n])->operator[](currentRow) = 0;
 						break;
 					case AbstractColumn::DateTime:
 						static_cast<QVector<QDateTime>*>(m_dataContainer[n])->operator[](currentRow) = QDateTime();
 						break;
 					case AbstractColumn::Text:
 						static_cast<QVector<QString>*>(m_dataContainer[n])->operator[](currentRow) = "";
 						break;
 					case AbstractColumn::Month:
 						//TODO
 						break;
 					case AbstractColumn::Day:
 						//TODO
 						break;
 					}
 				}
 			}
 			currentRow++;
 		}
 	}
 
 	if (m_prepared) {
 		//notify all affected columns and plots about the changes
 		PERFTRACE("AsciiLiveDataImport, notify affected columns and plots");
 		const Project* project = spreadsheet->project();
 		QVector<const XYCurve*> curves = project->children<const XYCurve>(AbstractAspect::Recursive);
 		QVector<CartesianPlot*> plots;
 		for (int n = 0; n < m_actualCols; ++n) {
 			Column* column = spreadsheet->column(n);
 
 			//determine the plots where the column is consumed
 			for (const auto* curve: curves) {
 				if (curve->xColumn() == column || curve->yColumn() == column) {
 					CartesianPlot* plot = dynamic_cast<CartesianPlot*>(curve->parentAspect());
 					if (plots.indexOf(plot) == -1) {
 						plots << plot;
 						plot->setSuppressDataChangedSignal(true);
 					}
 				}
 			}
 
 			column->setChanged();
 		}
 
 		//loop over all affected plots and retransform them
 		for (auto* plot: plots) {
 			plot->setSuppressDataChangedSignal(false);
 			plot->dataChanged();
 		}
 	}
 
 	m_prepared = true;
 
 	return bytesread;
 }
 
 /*!
     reads the content of device \c device to the data source \c dataSource. Uses the settings defined in the data source.
 */
 void AsciiFilterPrivate::readDataFromDevice(QIODevice& device, AbstractDataSource* dataSource, AbstractFileFilter::ImportMode importMode, int lines) {
 	DEBUG("AsciiFilterPrivate::readDataFromDevice(): dataSource = " << dataSource
 	      << ", mode = " << ENUM_TO_STRING(AbstractFileFilter, ImportMode, importMode) << ", lines = " << lines);
 
 	if (!m_prepared) {
 		const int deviceError = prepareDeviceToRead(device);
 		if (deviceError != 0) {
 			DEBUG("Device error = " << deviceError);
 			return;
 		}
 
 		// matrix data has only one column mode (which is not text)
 		if (dynamic_cast<Matrix*>(dataSource)) {
 			auto mode = columnModes[0];
 			if (mode == AbstractColumn::Text)
 				mode = AbstractColumn::Numeric;
 			for (auto& c: columnModes)
 				if (c != mode)
 					c = mode;
 		}
 
 		m_columnOffset = dataSource->prepareImport(m_dataContainer, importMode, m_actualRows, m_actualCols, vectorNames, columnModes);
 		m_prepared = true;
 	}
 
 	DEBUG("locale = " << QLocale::languageToString(numberFormat).toStdString());
 	QLocale locale(numberFormat);
 
 	// Read the data
 	int currentRow = 0;	// indexes the position in the vector(column)
 	if (lines == -1)
 		lines = m_actualRows;
 
 	//skip data lines, if required
 	DEBUG("	Skipping " << m_actualStartRow - 1 << " lines");
 	for (int i = 0; i < m_actualStartRow - 1; ++i)
 		device.readLine();
 
 	DEBUG("	Reading " << qMin(lines, m_actualRows)  << " lines");
 	for (int i = 0; i < qMin(lines, m_actualRows); ++i) {
 		QString line = device.readLine();
 
 		line.remove(QRegExp("[\\n\\r]"));	// remove any newline
 		if (simplifyWhitespacesEnabled)
 			line = line.simplified();
 
 		if (line.isEmpty() || line.startsWith(commentCharacter)) // skip empty or commented lines
 			continue;
 
 
 		QStringList lineStringList = line.split(m_separator, (QString::SplitBehavior)skipEmptyParts);
 
 		//prepend the index if required
 		//TODO: come up maybe with a solution with adding the index inside of the loop below,
 		//without conversion to string, prepending to the list and then conversion back to integer.
 		if (createIndexEnabled)
 			lineStringList.prepend(QString::number(i+1));
 
 		// remove left white spaces
 		if (skipEmptyParts) {
 			for (int n = 0; n < lineStringList.size(); ++n) {
 				QString valueString = lineStringList.at(n);
 				if (!QString::compare(valueString, " ")) {
 					lineStringList.removeAt(n);
 					n--;
 				}
 			}
 		}
 
 		for (int n = 0; n < m_actualCols; ++n) {
 			if (n < lineStringList.size()) {
 				QString valueString = lineStringList.at(n);
 
 				// set value depending on data type
 				switch (columnModes[n]) {
 				case AbstractColumn::Numeric: {
 					bool isNumber;
 					const double value = locale.toDouble(valueString, &isNumber);
 					static_cast<QVector<double>*>(m_dataContainer[n])->operator[](currentRow) = (isNumber ? value : nanValue);
 					break;
 				}
 				case AbstractColumn::Integer: {
 					bool isNumber;
 					const int value = locale.toInt(valueString, &isNumber);
 					static_cast<QVector<int>*>(m_dataContainer[n])->operator[](currentRow) = (isNumber ? value : 0);
 					break;
 				}
 				case AbstractColumn::DateTime: {
 					const QDateTime valueDateTime = QDateTime::fromString(valueString, dateTimeFormat);
 					static_cast<QVector<QDateTime>*>(m_dataContainer[n])->operator[](currentRow) = valueDateTime.isValid() ? valueDateTime : QDateTime();
 					break;
 				}
 				case AbstractColumn::Text:
 					if (removeQuotesEnabled)
 						valueString.remove(QRegExp("[\"\']"));
 					static_cast<QVector<QString>*>(m_dataContainer[n])->operator[](currentRow) = valueString;
 					break;
 				case AbstractColumn::Month:	// never happens
 				case AbstractColumn::Day:
 					break;
 				}
 			} else {	// missing columns in this line
 				switch (columnModes[n]) {
 				case AbstractColumn::Numeric:
 					static_cast<QVector<double>*>(m_dataContainer[n])->operator[](currentRow) = nanValue;
 					break;
 				case AbstractColumn::Integer:
 					static_cast<QVector<int>*>(m_dataContainer[n])->operator[](currentRow) = 0;
 					break;
 				case AbstractColumn::DateTime:
 					static_cast<QVector<QDateTime>*>(m_dataContainer[n])->operator[](currentRow) = QDateTime();
 					break;
 				case AbstractColumn::Text:
 					static_cast<QVector<QString>*>(m_dataContainer[n])->operator[](currentRow) = "";
 					break;
 				case AbstractColumn::Month:	// never happens
 				case AbstractColumn::Day:
 					break;
 				}
 			}
 		}
 
 		currentRow++;
 		emit q->completed(100 * currentRow/m_actualRows);
 	}
 
 	dataSource->finalizeImport(m_columnOffset, startColumn, endColumn, dateTimeFormat, importMode);
 }
 
 /*!
  * preview for special devices (local/UDP/TCP socket or serial port)
  */
 QVector<QStringList> AsciiFilterPrivate::preview(QIODevice &device) {
 	DEBUG("AsciiFilterPrivate::preview(): bytesAvailable = " << device.bytesAvailable() << ", isSequential = " << device.isSequential());
 	QVector<QStringList> dataStrings;
 
 	if (!(device.bytesAvailable() > 0)) {
 		DEBUG("No new data available");
 		return dataStrings;
 	}
 
 	if (device.isSequential() && device.bytesAvailable() < (int)sizeof(quint16))
 		return dataStrings;
 
 #ifdef PERFTRACE_LIVE_IMPORT
 	PERFTRACE("AsciiLiveDataImportTotal: ");
 #endif
 
 	int linesToRead = 0;
 	QVector<QString> newData;
 
 	while (!device.atEnd()) {
 		if (device.canReadLine())
 			newData.push_back(device.readLine());
 		else	// UDP fails otherwise
 			newData.push_back(device.readAll());
 		linesToRead++;
 	}
 	QDEBUG("	data = " << newData);
 
 	if (linesToRead == 0) return dataStrings;
 
 	int col = 0;
 	int colMax = newData.at(0).size();
 	if (createIndexEnabled)
 		colMax++;
 	columnModes.resize(colMax);
 	if (createIndexEnabled) {
 		columnModes[0] = AbstractColumn::ColumnMode::Integer;
 		col = 1;
 		vectorNames.prepend(i18n("Index"));
 	}
 	vectorNames.append(i18n("Value"));
 	QDEBUG("	vector names = " << vectorNames);
 
 	for (const auto& valueString: newData.at(0).split(' ', QString::SkipEmptyParts)) {
 		if (col == colMax)
 			break;
 		columnModes[col++] = AbstractFileFilter::columnMode(valueString, dateTimeFormat, numberFormat);
 	}
 
 	for (int i = 0; i < linesToRead; ++i) {
 		QString line = newData.at(i);
 
 		if (simplifyWhitespacesEnabled)
 			line = line.simplified();
 
 		if (line.isEmpty() || line.startsWith(commentCharacter)) // skip empty or commented lines
 			continue;
 
 		QLocale locale(numberFormat);
 
 		QStringList lineStringList = line.split(' ', QString::SkipEmptyParts);
 		if (createIndexEnabled)
 			lineStringList.prepend(QString::number(i));
 
 		QStringList lineString;
 		for (int n = 0; n < lineStringList.size(); ++n) {
 			if (n < lineStringList.size()) {
 				QString valueString = lineStringList.at(n);
 
 				switch (columnModes[n]) {
 				case AbstractColumn::Numeric: {
 					bool isNumber;
 					const double value = locale.toDouble(valueString, &isNumber);
 					lineString += QString::number(isNumber ? value : nanValue, 'g', 16);
 					break;
 				}
 				case AbstractColumn::Integer: {
 					bool isNumber;
 					const int value = locale.toInt(valueString, &isNumber);
 					lineString += QString::number(isNumber ? value : 0);
 					break;
 				}
 				case AbstractColumn::DateTime: {
 					const QDateTime valueDateTime = QDateTime::fromString(valueString, dateTimeFormat);
 					lineString += valueDateTime.isValid() ? valueDateTime.toString(dateTimeFormat) : QLatin1String(" ");
 					break;
 				}
 				case AbstractColumn::Text:
 					if (removeQuotesEnabled)
 						valueString.remove(QRegExp("[\"\']"));
 					lineString += valueString;
 					break;
 				case AbstractColumn::Month:	// never happens
 				case AbstractColumn::Day:
 					break;
 				}
 			} else 	// missing columns in this line
 				lineString += QLatin1String("");
 		}
 		dataStrings << lineString;
 	}
 
 	return dataStrings;
 }
 
 /*!
  * generates the preview for the file \c fileName reading the provided number of \c lines.
  */
 QVector<QStringList> AsciiFilterPrivate::preview(const QString& fileName, int lines) {
 	QVector<QStringList> dataStrings;
 
 	KFilterDev device(fileName);
 	const int deviceError = prepareDeviceToRead(device);
 	if (deviceError != 0) {
 		DEBUG("Device error = " << deviceError);
 		return dataStrings;
 	}
 
 	//number formatting
 	DEBUG("locale = " << QLocale::languageToString(numberFormat).toStdString());
 	QLocale locale(numberFormat);
 
 	// Read the data
 	if (lines == -1)
 		lines = m_actualRows;
 
 	// set column names for preview
 	if (!headerEnabled) {
 		int start = 0;
 		if (createIndexEnabled)
 			start = 1;
 		for (int i=start;i<m_actualCols;i++)
 				vectorNames << "Column " + QString::number(i+1);
 	}
 	QDEBUG("	column names = " << vectorNames);
 
 	//skip data lines, if required
 	DEBUG("	Skipping " << m_actualStartRow - 1 << " lines");
 	for (int i = 0; i < m_actualStartRow - 1; ++i)
 		device.readLine();
 
 	DEBUG("	Generating preview for " << qMin(lines, m_actualRows)  << " lines");
 	for (int i = 0; i < qMin(lines, m_actualRows); ++i) {
 		QString line = device.readLine();
 
 		line.remove(QRegExp("[\\n\\r]"));	// remove any newline
 		if (simplifyWhitespacesEnabled)
 			line = line.simplified();
 
 		if (line.isEmpty() || line.startsWith(commentCharacter)) // skip empty or commented lines
 			continue;
 
 
 		QStringList lineStringList = line.split(m_separator, (QString::SplitBehavior)skipEmptyParts);
 		QDEBUG(" line = " << lineStringList);
 
 		//prepend index if required
 		if (createIndexEnabled)
 			lineStringList.prepend(QString::number(i+1));
 
 		QStringList lineString;
 		for (int n = 0; n < m_actualCols; ++n) {
 			if (n < lineStringList.size()) {
 				QString valueString = lineStringList.at(n);
 				//DEBUG(" valueString = " << valueString.toStdString());
 				if (skipEmptyParts && !QString::compare(valueString, " "))	// handle left white spaces
 					continue;
 
 				// set value depending on data type
 				switch (columnModes[n]) {
 				case AbstractColumn::Numeric: {
 					bool isNumber;
 					const double value = locale.toDouble(valueString, &isNumber);
 					lineString += QString::number(isNumber ? value : nanValue, 'g', 15);
 					break;
 				}
 				case AbstractColumn::Integer: {
 					bool isNumber;
 					const int value = locale.toInt(valueString, &isNumber);
 					lineString += QString::number(isNumber ? value : 0);
 					break;
 				}
 				case AbstractColumn::DateTime: {
 					const QDateTime valueDateTime = QDateTime::fromString(valueString, dateTimeFormat);
 					lineString += valueDateTime.isValid() ? valueDateTime.toString(dateTimeFormat) : QLatin1String(" ");
 					break;
 				}
 				case AbstractColumn::Text:
 					if (removeQuotesEnabled)
 						valueString.remove(QRegExp("[\"\']"));
 					lineString += valueString;
 					break;
 				case AbstractColumn::Month:	// never happens
 				case AbstractColumn::Day:
 					break;
 				}
 			} else 	// missing columns in this line
 				lineString += QLatin1String("");
 		}
 
 		dataStrings << lineString;
 	}
 
 	return dataStrings;
 }
 
 /*!
     writes the content of \c dataSource to the file \c fileName.
 */
 void AsciiFilterPrivate::write(const QString & fileName, AbstractDataSource* dataSource) {
 	Q_UNUSED(fileName);
 	Q_UNUSED(dataSource);
 
 	//TODO: save data to ascii file
 }
 
 //##############################################################################
 //##################  Serialization/Deserialization  ###########################
 //##############################################################################
 /*!
   Saves as XML.
  */
 void AsciiFilter::save(QXmlStreamWriter* writer) const {
 	writer->writeStartElement( "asciiFilter");
 	writer->writeAttribute( "commentCharacter", d->commentCharacter);
 	writer->writeAttribute( "separatingCharacter", d->separatingCharacter);
 	writer->writeAttribute( "autoMode", QString::number(d->autoModeEnabled));
 	writer->writeAttribute( "createIndex", QString::number(d->createIndexEnabled));
 	writer->writeAttribute( "header", QString::number(d->headerEnabled));
 	writer->writeAttribute( "vectorNames", d->vectorNames.join(' '));
 	writer->writeAttribute( "skipEmptyParts", QString::number(d->skipEmptyParts));
 	writer->writeAttribute( "simplifyWhitespaces", QString::number(d->simplifyWhitespacesEnabled));
 	writer->writeAttribute( "nanValue", QString::number(d->nanValue));
 	writer->writeAttribute( "removeQuotes", QString::number(d->removeQuotesEnabled));
 	writer->writeAttribute( "startRow", QString::number(d->startRow));
 	writer->writeAttribute( "endRow", QString::number(d->endRow));
 	writer->writeAttribute( "startColumn", QString::number(d->startColumn));
 	writer->writeAttribute( "endColumn", QString::number(d->endColumn));
 
 	writer->writeEndElement();
 }
 
 /*!
   Loads from XML.
 */
 bool AsciiFilter::load(XmlStreamReader* reader) {
 	KLocalizedString attributeWarning = ki18n("Attribute '%1' missing or empty, default value is used");
 	QXmlStreamAttributes attribs = reader->attributes();
 
 	QString str = attribs.value("commentCharacter").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("commentCharacter").toString());
 	else
 		d->commentCharacter = str;
 
 	str = attribs.value("separatingCharacter").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("separatingCharacter").toString());
 	else
 		d->separatingCharacter = str;
 
 	str = attribs.value("createIndex").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("createIndex").toString());
 	else
 		d->createIndexEnabled = str.toInt();
 
 	str = attribs.value("autoMode").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("autoMode").toString());
 	else
 		d->autoModeEnabled = str.toInt();
 
 	str = attribs.value("header").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("header").toString());
 	else
 		d->headerEnabled = str.toInt();
 
 	str = attribs.value("vectorNames").toString();
 	d->vectorNames = str.split(' '); //may be empty
 
 	str = attribs.value("simplifyWhitespaces").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("simplifyWhitespaces").toString());
 	else
 		d->simplifyWhitespacesEnabled = str.toInt();
 
 	str = attribs.value("nanValue").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("nanValue").toString());
 	else
 		d->nanValue = str.toDouble();
 
 	str = attribs.value("removeQuotes").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("removeQuotes").toString());
 	else
 		d->removeQuotesEnabled = str.toInt();
 
 	str = attribs.value("skipEmptyParts").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("skipEmptyParts").toString());
 	else
 		d->skipEmptyParts = str.toInt();
 
 	str = attribs.value("startRow").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("startRow").toString());
 	else
 		d->startRow = str.toInt();
 
 	str = attribs.value("endRow").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("endRow").toString());
 	else
 		d->endRow = str.toInt();
 
 	str = attribs.value("startColumn").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("startColumn").toString());
 	else
 		d->startColumn = str.toInt();
 
 	str = attribs.value("endColumn").toString();
 	if (str.isEmpty())
 		reader->raiseWarning(attributeWarning.subs("endColumn").toString());
 	else
 		d->endColumn = str.toInt();
 
 	return true;
 }
diff --git a/src/backend/datasources/filters/AsciiFilterPrivate.h b/src/backend/datasources/filters/AsciiFilterPrivate.h
index 71d8656ac..e26c8dfc1 100644
--- a/src/backend/datasources/filters/AsciiFilterPrivate.h
+++ b/src/backend/datasources/filters/AsciiFilterPrivate.h
@@ -1,86 +1,86 @@
 /***************************************************************************
     File                 : AsciiFilterPrivate.h
     Project              : LabPlot
     Description          : Private implementation class for AsciiFilter.
     --------------------------------------------------------------------
     Copyright            : (C) 2009-2013 Alexander Semke (alexander.semke@web.de)
     Copyright            : (C) 2017 Stefan Gerlach (stefan.gerlach@uni.kn)
 
  ***************************************************************************/
 
 /***************************************************************************
  *                                                                         *
  *  This program is free software; you can redistribute it and/or modify   *
  *  it under the terms of the GNU General Public License as published by   *
  *  the Free Software Foundation; either version 2 of the License, or      *
  *  (at your option) any later version.                                    *
  *                                                                         *
  *  This program is distributed in the hope that it will be useful,        *
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of         *
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          *
  *  GNU General Public License for more details.                           *
  *                                                                         *
  *   You should have received a copy of the GNU General Public License     *
  *   along with this program; if not, write to the Free Software           *
  *   Foundation, Inc., 51 Franklin Street, Fifth Floor,                    *
  *   Boston, MA  02110-1301  USA                                           *
  *                                                                         *
  ***************************************************************************/
 
 #ifndef ASCIIFILTERPRIVATE_H
 #define ASCIIFILTERPRIVATE_H
 
 class KFilterDev;
 class AbstractDataSource;
 class AbstractColumn;
 
 class AsciiFilterPrivate {
 
 public:
 	explicit AsciiFilterPrivate(AsciiFilter*);
 
 	QStringList getLineString(QIODevice&);
 	int prepareDeviceToRead(QIODevice&);
 	void readDataFromDevice(QIODevice&, AbstractDataSource* = nullptr,
 			AbstractFileFilter::ImportMode = AbstractFileFilter::Replace, int lines = -1);
 	void readFromLiveDeviceNotFile(QIODevice& device, AbstractDataSource*,
 			AbstractFileFilter::ImportMode = AbstractFileFilter::Replace);
 	qint64 readFromLiveDevice(QIODevice&, AbstractDataSource*, qint64 from = -1);
 	void readDataFromFile(const QString& fileName, AbstractDataSource* = nullptr,
 			AbstractFileFilter::ImportMode = AbstractFileFilter::Replace);
 	void write(const QString& fileName, AbstractDataSource*);
 	QVector<QStringList> preview(const QString& fileName, int lines);
 	QVector<QStringList> preview(QIODevice& device);
 
 	const AsciiFilter* q;
 
 	QString commentCharacter;
 	QString separatingCharacter;
 	QString dateTimeFormat;
 	QLocale::Language numberFormat;
 	bool autoModeEnabled;
 	bool headerEnabled;
 	bool skipEmptyParts;
 	bool simplifyWhitespacesEnabled;
 	double nanValue;
 	bool removeQuotesEnabled;
 	bool createIndexEnabled;
 	QStringList vectorNames;
 	QVector<AbstractColumn::ColumnMode> columnModes;
 	int startRow;
 	int endRow;
 	int startColumn;
 	int endColumn;
 
 private:
-	static const unsigned int m_dataTypeLines = 10;	// lines to read for determining data types
+	static const unsigned int m_dataTypeLines = 10;	// maximum lines to read for determining data types
 	QString m_separator;
 	int m_actualStartRow;
 	int m_actualRows;
 	int m_actualCols;
 	int m_prepared;
 	int m_columnOffset; // indexes the "start column" in the datasource. Data will be imported starting from this column.
 	QVector<void*> m_dataContainer; // pointers to the actual data containers
 };
 
 #endif