When you have the program PROPERLY set up, the axis will move to the limit switch at the Homing speed set in the ini. When the switch "trips", the axis will reverse until the switch "un-trips". Depending on the type of switch, this could be several .010s" or it might be nil in the case of an optical.
If you do a G28, ALL axis will move to home and each one will stop. Then each will reverse direction until home. You can (when the program is working right) home a single axis in the jog screen and it will act as indicated above.
IF it just goes to the home switch and stops (no reversal) then you do not have the paramaters properly set up (as me how I know
If you want a version of 4.01 that will do single axis homing under G28, let me know as I have compiled a version that works for me.