Thank you BobM3. Yes I hold deadman switch right, than I turn on the on/off switch at teach pendant but the LCD is light but no any information in it. If I release deadman switch the Fault LED will light up. In my control panel only have a Remote on/off switch. It use for on/off the panel enabled LED. But it no switch on control panel to on/off the teach pendant enabled LED. My teach pendant type: A05B-2051-C142. Do you think any way will lock or disabled the teach pendant enabled function at robot parameter, program or PLC port?