private void cmbCarbinetIndex_SelectedIndexChanged(object sender, EventArgs e)
{
this.ClearListenerAndStopRunning();
this.ClearControls();
this.current_helper = helperList[this.cmbCarbinetIndex.SelectedIndex];
this.current_helper.start(this);
}
void initialHelperList()
{
EpcProductHelper helper1 = new EpcProductHelper(this.listening_port1);
this.helperList.Add(helper1);
EpcProductHelper helper2 = new EpcProductHelper(this.listening_port2);
this.helperList.Add(helper2);
EpcProductHelper helper3 = new EpcProductHelper(this.listening_port3);
this.helperList.Add(helper3);
EpcProductHelper helper4 = new EpcProductHelper(this.listening_port4);
this.helperList.Add(helper4);
}