private void cbbserialport_SelectedIndexChanged(object sender, EventArgs e) { try { serialPortManager.SetComPortManual(cbbserialport.SelectedItem.ToString()); serialPortManager.SetComSpeedManual(1000000); serialPortManager.Open(); btnFire.Enabled = true; } catch { btnFire.Enabled = false; MessageBox.Show("Can't open the COM port", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); } }