After Effects Autoscroll - Vertical Animation Preset Issue

Question

Hi After Effects Community,
I am hoping someone can assist me with an issue I have been unable to work out when applying the Autoscroll Vertical Animation preset in After Effects CC. I have already spent ages working way through the forums and googling topic but not quite found the answer, so here goes:
Trying to create scrolling credits for a film I am are editing. Normally, I use the titler in Premiere Pro CC for this and then use the scroll setting. This works to a point but it is very limited in terms of editing/formatting and I have been trying to create a template in After Effects where by you can simply go in and edit the text in the layers and drop the new credit roll into any project.
Taking advice from a source online (Trish Meyer I think), I created a new comp (1920 x 1080 @ 25fps and 2 mins long) and then created a precomp inside this and created all my text. I adjusted the size of this comp so that all the text layers fit onto it. This made it very long (dimensions of precomp are 1920 x 16000. Other settings matched the main composition). I then went back to my main comp and applied the Autoscroll Vertical Animation preset behaviour effect. I thought this was it as the effect did create a scroll but I found that it didn't start the roll from the beginning of my text, rather half way down, and also only scrolled so far before it stopped scrolling.
Does anyone have any advice or recommendations as to what I need to do here to create the desired effect? Ideally I need it to roll through the credit text and then slowly stop on last line of credits before fading to black. I notice that the Motion Tile section of the preset effect has numbers that are red (numbers relate to Tile Centre) and assume this links to the expression attached to this effect.
Do I need to animate the centre of the tile? I saw something online about there being a maximum number of frames the After Effects can render or something like this which is why the animation stops. I must admit I can't believe that this is such a hard thing to learn how to do as I would have thought it is a basic that most film makers would need to do at some point yet it is not well covered online in the form of tutorials etc.
Anyway, I would be so grateful if anyone is able to help. If it is easier I am willing to upload my AE project file so that people can take a closer look to see in more detail what I have tried to explain here.
Many thanks,
Alex

Answer 1

One way to create the correct timing is to create 2 keyframes for position that are 1 frame apart. set the y value for the second key frame to be the number of pixels per frame movement that you need (say 2 pixels). then add this expression: loopOut('continue') the movement will not happen until time hits the first keyframe, so timing can be adjusted in a more familiar way, then the code just continues that movement.
You might add this animation and expression to a null, then parent the credits to the null to make it easy to adjust the credit position separate from the animation. Also, you can split the layer at the point you want it to stop moving and undo the parent for it.