Real time graph plotting using zedgraph

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C#

UDP

ZedGraph

Hi,
I'am developed one c# application in which i want to update graph real time data receiving from
udp & plot it accordingly different conditions in 13 controls of zed graph control also dump
data to file also. Second part works fine but graph plotting is not done correctly.
Below i paste code for both module,please suggest any change or show logical error in code.
1. Code for save data in file also add to rollingpointpairlist buffer.

private void updateFile() {
           f = new Form1();
            for (int i = 0; i < arrLen; ) {
                chnId = buff[i];
                ushort smpCnt = toUInt16(buff, i + 1);

                if (chnId > 12) {
                    log.WriteLine("{0:D}\t{1:D} ???", new object[] { chnId, smpCnt });
                    return;
                }
                i += 3;
                try {
                    if (BitConverter.IsLittleEndian) {
                        for (int j = 0; j < smpCnt * chnCnt[chnId]; j++) {
                            for (int k = 0; k < smpSize[chnId]; k++)
                                smpData[(j + 1) * smpSize[chnId] - k] = buff[j * smpSize[chnId] + k];
                        }
                        fs[chnId].Write(smpData, 0, smpSize[chnId] * smpCnt * chnCnt[chnId]);
                        f.fillBuffer(smpData,chnId);//Here i add data to rolling point pairlist for plot into graph

}
2. code for insert data in rolling buffer according to condition on chId

public void fillBuffer(byte[] data, int chId)
        {
            int bufLength = data.Length;
            double[] plotData = new double[data.Length];

                 switch (chId)
                    {
                        case 0:
                            intrptval1 -= initTimer;
                            if (intrptval1 <= 0)
                            {
                                updtGraph(ch0.tSmpCh1, data, bufLength, ch0.plotBuff1, zedGraphControl1, ch0.pane1);
                                ch0.definedCntValues1 = ch0.valToSet1;
                                bufLength -= bufLength;
                            }
                            break;
}
}

3. Code for update graph

private void updtGraph(double smpTime, byte[] data, int ptsToPlot, RollingPointPairList rollBuff, ZedGraphControl ctrl, GraphPane pane)
       {
           pane = ctrl.GraphPane;
           double[]  plotData = new double[data.Length];
        //  double[] plotData = toDouble(data, 0);

           try
           {
               for (int index = 0; index < ptsToPlot; index++)
               {
                   plotData[index] = toDouble(data, index);
                   startTimer += smpTime;
                   rollBuff.Add(startTimer, plotData[index]);

                   Scale xScale1 = ctrl.GraphPane.XAxis.Scale;
                   double delta = startTimer - rollBuff[0].X;
                   if (delta > smpTime * ptsToPlot - 1)
                   {
                       xScale1.Min = startTimer - smpTime * (ptsToPlot);
                       xScale1.Max = startTimer + smpTime;
                   }
                   else
                   {
                       xScale1.Min = rollBuff[0].X;
                       xScale1.Max = rollBuff[0].X + smpTime * (ptsToPlot);
                   }
                   ctrl.AxisChange();
                   ctrl.Invalidate();
                   ctrl.Refresh();
               }
}