Hi Marco,
thank you very much for your response. I have gone through above link and found info as "
Controller version 2.80 or higher supports maintenance mode. Right-clicking one or more Robots in the Infrastructure Manager main window pane, selecting Maintenance, lets you set the selected Robot (s) into maintenance mode for the period specified
."
When I right click on robot, I don't see maintenance option, Instead it is listing new,restart,remove,Properties.