You have to set it with the tower and then the direction is fixed.
Note I found a bug the other night. When it reports that its direction setting is "right" and you want to change to "left" you have to do the following: drill down the menu to analog mode, d'rctn, if it says "right" then with the side arrows move to "left" then on again to "right" and hit select. Although you now appear to have chosen the same one you were on if you go up the menu and back down you will find it now reports as "left" and the cars will go the opposite way.
Sure confused the hell out of me for an evening!
Note I found a bug the other night. When it reports that its direction setting is "right" and you want to change to "left" you have to do the following: drill down the menu to analog mode, d'rctn, if it says "right" then with the side arrows move to "left" then on again to "right" and hit select. Although you now appear to have chosen the same one you were on if you go up the menu and back down you will find it now reports as "left" and the cars will go the opposite way.
Sure confused the hell out of me for an evening!