diff --git a/src/asciireader.cpp b/src/asciireader.cpp
--- a/src/asciireader.cpp
+++ b/src/asciireader.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -142,21 +142,24 @@ void AsciiReader::onDataReady()
         }
 
         // parse read line
+        double* channelSamples = new double[_numOfChannels]();
         for (unsigned ci = 0; ci < numReadChannels; ci++)
         {
             bool ok;
-            double channelSample = separatedValues[ci].toDouble(&ok);
-            if (ok)
-            {
-                _channelMan->addChannelData(ci, &channelSample, 1);
-                sampleCount++;
-            }
-            else
+            channelSamples[ci] = separatedValues[ci].toDouble(&ok);
+            if (!ok)
             {
                 qWarning() << "Data parsing error for channel: " << ci;
+                channelSamples[ci] = 0;
             }
         }
+
+        // commit data
+        _channelMan->addData(channelSamples, _numOfChannels);
+        sampleCount += numReadChannels;
         emit dataAdded();
+
+        delete[] channelSamples;
     }
 }
 
diff --git a/src/binarystreamreader.cpp b/src/binarystreamreader.cpp
--- a/src/binarystreamreader.cpp
+++ b/src/binarystreamreader.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -171,12 +171,8 @@ void BinaryStreamReader::onDataReady()
         }
     }
 
-    for (unsigned int ci = 0; ci < _numOfChannels; ci++)
-    {
-        addChannelData(ci,
-                       channelSamples + ci*numOfPackagesToRead,
-                       numOfPackagesToRead);
-    }
+    _channelMan->addData(channelSamples, numOfPackagesToRead*_numOfChannels);
+    sampleCount += numOfPackagesToRead*_numOfChannels;
     emit dataAdded();
 
     delete[] channelSamples;
@@ -200,13 +196,6 @@ template<typename T> double BinaryStream
     return double(data);
 }
 
-void BinaryStreamReader::addChannelData(unsigned int channel,
-                                        double* data, unsigned size)
-{
-    _channelMan->addChannelData(channel, data, size);
-    sampleCount += size;
-}
-
 void BinaryStreamReader::saveSettings(QSettings* settings)
 {
     _settingsWidget.saveSettings(settings);
diff --git a/src/binarystreamreader.h b/src/binarystreamreader.h
--- a/src/binarystreamreader.h
+++ b/src/binarystreamreader.h
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -65,9 +65,6 @@ private:
      */
     template<typename T> double readSampleAs();
 
-    // `data` contains i th channels data
-    void addChannelData(unsigned int channel, double* data, unsigned size);
-
 private slots:
     void onNumberFormatChanged(NumberFormat numberFormat);
     void onNumOfChannelsChanged(unsigned value);
diff --git a/src/channelmanager.cpp b/src/channelmanager.cpp
--- a/src/channelmanager.cpp
+++ b/src/channelmanager.cpp
@@ -161,9 +161,15 @@ void ChannelManager::onChannelInfoChange
     }
 }
 
-void ChannelManager::addChannelData(unsigned channel, double* data, unsigned size)
+void ChannelManager::addData(double* data, unsigned size)
 {
-    channelBuffer(channel)->addSamples(data, size);
+    Q_ASSERT(size % _numOfChannels == 0);
+
+    int n = size / _numOfChannels;
+    for (unsigned ci = 0; ci < _numOfChannels; ci++)
+    {
+        channelBuffers[ci]->addSamples(&data[ci*n], n);
+    }
 }
 
 void ChannelManager::saveSettings(QSettings* settings)
diff --git a/src/channelmanager.h b/src/channelmanager.h
--- a/src/channelmanager.h
+++ b/src/channelmanager.h
@@ -58,7 +58,18 @@ signals:
 public slots:
     void setNumOfChannels(unsigned number);
     void setNumOfSamples(unsigned number);
-    void addChannelData(unsigned channel, double* data, unsigned size);
+    /**
+     * Add data for all channels.
+     *
+     * All channels data is provided in a single array which contains equal
+     * number of samples for all channels. Structure is as shown below:
+     *
+     * [CH0_SMP0, CH0_SMP1 ... CH0_SMPN, CH1_SMP0, CH1_SMP1, ... , CHN_SMPN]
+     *
+     * @param data samples for all channels
+     * @param size size of `data`, must be multiple of `numOfChannels`
+     */
+    void addData(double* data, unsigned size);
 
 private:
     unsigned _numOfChannels;
diff --git a/src/demoreader.cpp b/src/demoreader.cpp
--- a/src/demoreader.cpp
+++ b/src/demoreader.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -76,13 +76,15 @@ void DemoReader::demoTimerTimeout()
 
     if (!paused)
     {
+        double* samples = new double[_numOfChannels];
         for (unsigned ci = 0; ci < _numOfChannels; ci++)
         {
             // we are calculating the fourier components of square wave
-            double value = 4*sin(2*M_PI*double((ci+1)*count)/period)/((2*(ci+1))*M_PI);
-            _channelMan->addChannelData(ci, &value, 1);
+            samples[ci] = 4*sin(2*M_PI*double((ci+1)*count)/period)/((2*(ci+1))*M_PI);
             sampleCount++;
         }
+        _channelMan->addData(samples, _numOfChannels);
+        delete[] samples;
         emit dataAdded();
     }
 }
diff --git a/src/framedreader.cpp b/src/framedreader.cpp
--- a/src/framedreader.cpp
+++ b/src/framedreader.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -310,14 +310,7 @@ void FramedReader::readFrameDataAndCheck
     if (!checksumEnabled || checksumPassed)
     {
         // commit data
-        for (unsigned int ci = 0; ci < _numOfChannels; ci++)
-        {
-            _channelMan->addChannelData(
-                ci,
-                channelSamples + ci*numOfPackagesToRead,
-                numOfPackagesToRead);
-            sampleCount += numOfPackagesToRead;
-        }
+        _channelMan->addData(channelSamples, numOfPackagesToRead * _numOfChannels);
         emit dataAdded();
     }
     else
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -149,6 +149,7 @@ MainWindow::MainWindow(QWidget *parent) 
     QObject::connect(&(this->serialPort), SIGNAL(error(QSerialPort::SerialPortError)),
                      this, SLOT(onPortError(QSerialPort::SerialPortError)));
 
+    // TODO: `replot` must be triggered from ChannelManager
     // init data format and reader
     QObject::connect(&dataFormatPanel, &DataFormatPanel::dataAdded,
                      plotMan, &PlotManager::replot);