The two kings cannot face each other directly vertically. They have to be blocked by at least one chessman of either side in the between. When a Cannon moves without taking, this is just like a normal rook. However, when a cannon makes a capture, he moves horizontally or vertically, and must jump over another piece before making the capture. Cannons capture by jumping over a piece to capture the next piece.
Cannons only capture when jumping, and only jump when capturing.
It can never jump over more than one piece at one time. In Chinese Chess, when a pawn is at his own side of the board, he can move one square straight forward. When a pawn has the river crossed and hence is at the opponents side of the board, he can either move one square straight forward, or one square horizontally to either direction. Again, there are different symbols for a red and a black pawn. The red player moves first.