Because it's attached to a rope, it has a max range of 50 feet, but an optimal range of 30. Assuming that Orchid's movement wasn't slowed down while he was climbing, his last turn had him run back 30 too the tower, and use the rest of his move action to climb 30 feet. This round he did another climb up to 30 feet, so he's about 60 feet up the tower wall and closer to the dragon.

If he isn't, then I'll just have Orchid keep climbing. How tall is this tower?