I really like making meaties moves,but most of the time I have troubles trying to do them due to not knowing the knockdown frames of,for example,a c.HK.Even if I search for the frame data most of the times it doesn’t appear so,is there any way to know how many knockdown frames does a move give?
The time someone is knocked down depends on a characters’ wake up frames and not the moves themself. The only difference between moves if they cause a hard or a soft kdown. wiki.shoryuken.com/Super_Street_Fighter_IV_AE/Universal_Abilities#Wake-Ups
Yeah and no,I mean yeah,you’re right that they also depend on characters (for example I BELIVE Sagat wakeups 1 frame slower than avarage) but a lot of moves gives diferent HARD knockdown frames,like Makoto for example,her EX Oroshi gives you 68 frames of ‘‘advantage’’ until opponenet wakes up and her c.HP gives just 45 frames.I’m just asking for a way to know how many frames or somewhere where I can see them
I might be wrong on this but doesn’t the recovery and/or +on hit affect that? Where’s ethernal when you need him?
In most frame data charts in the + on hit part of the moves that knockdown are -…just -… 
. The recovery wouldn’t affect much except if some short of trade or meaty happens as the knockdown frames are like the advantage on hit you got…Damn I suck at explaining things and I suck more if I have to do it in english.
There is no single source available for knockdown advantage in frames- you would have to test the moves individually. The timings are not even available in the game’s files because many (not all) knockdowns are generated through the game’s physics, which is why certain juggles, like akuma’s tatsu into sweep, are character specific.
The timings listed on the wiki refer only to the actual wakeup animations themselves, and not the knockdown animations.
You can record a dummy reversal on wake up with a capture card and watch frame by frame to count.
You can make a script with SF4 Show-off and find out by trial and error.