"Conditional" Command Blocks[edit source]
All command blocks use this feature, not just Chain command blocks. Furthermore, all command blocks check behind themselves, including Chain blocks, rather than in sequence ("previous"). In this image, #4 is set to conditional and requires #1 to be successful in output, not #3. It needs #3 in order to connect to the chain of commands.
Impulse blocks behave as expected (image); the command block on the right is conditional but cannot run its command unless the one "behind" it (opposite of its facing) is successful.
Repeating blocks are the same as Impulse blocks, except they will not constantly send a signal if the block behind them was unsuccessful.
And while a conditional command block does not run its command if the block behind it fails, it will still push a signal through chain blocks. That means in this image, if the Repeating block is conditional and fails, all the chain blocks are activated once. Since it's a Repeating block, it will not send a signal after that point until a block behind it is successful. It's the same for Impulse blocks, minus the fact that they can't clock.
- I think I see what you're saying. I'll make a stab at correcting the article. —munin · · 20:20, 20 August 2015 (UTC)
DEFAULT Setting for Chain blocks[edit source]
Chain command blocks all defaults to "always active", meaning they will activate depends on what chained to it, regardless the redstone.