//In fact,when you are using the tcp/ip communication,this parameter will be ignored,that is any integer will all right.Here we use 1. iMachineNumber = 1; //Here you can register the realtime events that you want to be triggered(the parameters 65535 means registering all) if (axCZKEM1.RegEvent(iMachineNumber, 65535)) { this.axCZKEM1.OnDisConnected += new zkemkeeper._IZKEMEvents_OnDisConnectedEventHandler(axCZKEM1_OnDisConnected); } private void axCZKEM1_OnDisConnected() { MessageBox.Show("RTEvent OnDisConnected Has been Triggered"); }