save data in DataGridView to XmlTextwriter

private void BAddStepLimit_Click(object sender, EventArgs e)
        {
            steplimitdr = spq.steplimitdt.NewRow();
            steplimitdr["stepnumberstlt"] = stepnum;
            steplimitdr["numberstlt"] = dataGridView3.RowCount + 1;
            steplimitdr["normname"] = LNormNameStLt.Text;
            steplimitdr["highwarning"] = NHighWarning.Value;
            steplimitdr["highshutdown"] = NHighshutDown.Value;
            steplimitdr["lowwarning"] = NLowWarning.Value;
            steplimitdr["lowshutdown"] = NLowShutDown.Value;
            steplimitdr["limitholdtime"] = NLimitholdTime.Value;
            if (CBUpperReact.SelectedIndex > -1)
            {
                steplimitdr["upperreact"] = CBUpperReact.Items[CBUpperReact.SelectedIndex];
            }
            if(CBLowerReact.SelectedIndex>-1)
            {
            steplimitdr["lowerreact"] = CBLowerReact.Items[CBLowerReact.SelectedIndex];
            }
            spq.steplimitdt.Rows.Add(steplimitdr);
            bindingSource2.DataSource = spq.steplimitdt;
            dataGridView4.DataSource = bindingSource2.DataSource;
            
        }

DataTable dt = sq.stepdt;
                        
                        for (int i = 0; i <= dt.Rows.Count-1; i++)
                        {
                            writer.WriteStartElement("Record1");
                            
                            writer.WriteAttributeString("number", tablestep.Rows[i].Cells[0].Value.ToString());
                            writer.WriteAttributeString("stepnumstep", tablestep.Rows[i].Cells[1].Value.ToString());
                            writer.WriteAttributeString("name", tablestep.Rows[i].Cells[2].Value.ToString());
                            writer.WriteAttributeString("description", tablestep.Rows[i].Cells[3].Value.ToString());
                            writer.WriteAttributeString("condition", tablestep.Rows[i].Cells[4].Value.ToString());
                            writer.WriteAttributeString("loopcount", tablestep.Rows[i].Cells[5].Value.ToString());
                            writer.WriteAttributeString("recorder", tablestep.Rows[i].Cells[6].Value.ToString());
                            writer.WriteAttributeString("dyabbreviation", tablestep.Rows[i].Cells[7].Value.ToString());
                            writer.WriteAttributeString("dydynovalue", tablestep.Rows[i].Cells[8].Value.ToString());
                            writer.WriteAttributeString("dyramp", tablestep.Rows[i].Cells[9].Value.ToString());
                            writer.WriteAttributeString("enabbreviation", tablestep.Rows[i].Cells[10].Value.ToString());
                            writer.WriteAttributeString("enenginevalue", tablestep.Rows[i].Cells[11].Value.ToString());
                            writer.WriteAttributeString("enramp", tablestep.Rows[i].Cells[12].Value.ToString());
                            writer.WriteAttributeString("max", tablestep.Rows[i].Cells[13].Value.ToString());
                            writer.WriteAttributeString("holdtime", tablestep.Rows[i].Cells[14].Value.ToString());
                            writer.WriteAttributeString("sample", tablestep.Rows[i].Cells[15].Value.ToString());
                            writer.WriteAttributeString("steptime", tablestep.Rows[i].Cells[16].Value.ToString());
                            writer.WriteEndElement();
                        }