I found Action Code 156 - software control for the keypad back light - whilst rebuilding my system. Ah, I thought, a nice way to elegantly control the KP lighting depending on the ambient light. Switch on when the light sensor detects dark outside and off when light outside.
Only problem is that when the pad is lit and used to login, exiting the KP automatically turns the back light off irrespective of the prior 156 ON command.
Is there a way round this so that KP use does not override the AC156?