Mark's note: Quoting from www.chentaichi.com:

Cannon fist is the application exercise in Chen style Taichi. It operates small circles in a fast, impulsive manner.
Normally, students need to practice the old form for three years before they are prepared for the cannon fist. Without thorough training in relaxation, balance and accuracy that one can benifit from the rather slower movements within the old form, cannon fist practice will be inaccurately practiced.

Start from explosive moves
1/ Initial form
2/ Six seals & four closures, Single whip
3/ Heart protecting fists.
4/ Jump step oblique form.
5/ Turn around Buddha's stamp

Then 6 to 10 is a strike section.
6/ Looking back shoulder strike.
7/ Cut hands
8/ Flipping flower flying sleeves.
9/ Hidden hand jump punch.
10/ Elbow strike.

This is a smooth and rest period
11/ Large arm and fist
12/ Small arm and fist

13 to 15 are fast stepping forward
13/ Fair lady operate shuttle.
14/ Back ride dragon (Dao Chi Lin)

Practice shaking energy
15/ Hidden hand punch
16/ Wrapping cracker

Step back and step up for long strike
17/ Elbow form
18/ Splitting form
19/ Hidden hand punch

Lower down and drag backward then strike forward
20/ Tame tiger.
22/ Dragon stir water.

Both side kicks
23/ Dash Leftward
24/ Dash Rightward
25/ Hidden hand punch

One leg stand Turn 270 D around
26/ Swipe shin leg
27/ Hidden hand punch

Two arms draw circles and strike fists forward
28/ Two fists strike
29/ Strike downward
30/ Hidden hand punch

Fast punches
31/ Cross step forearm strike

Long jump and turn with fists striking
32/ Big change Jump
33/ Turn around cannon fists

Continuous fast stepping and side strikes
34/ Waist elbow strike.
35/ Twist elbow strike
36/ Elbow heart strike
37/ Turn around go straight in.

End
38/ Buddha's stamp.

list from www.chentaichi.com