Command Block always activates Comparator

Question

I am trying to do something with command blocks. I have it test for a player at a certain position. I have set up a hopper clock that activates a command block with

/testfor @a[x=-611,y=80,z=714]

For some reason, no matter where i stand, the command block will always produce a redstone signal. Even though when I check the "last output" it says that the player can't be found.

I think I figured it out, the redstone comparator is picking up a signal from the block like its a regular block, but I do not know how to fix this.

Screenshots (open in new tab to enlarge):

Answer 1

When using coordinates, you need to specify a radius so that it knows how far to search from that specific point. Try changing your command to:

/testfor @a[x=-611,y=80,z=714,r=1]

You can also compact it down into:

/testfor @a[-611,80,714,1]

I believe that the reason is that without a radius the selector makes no sense, so it is simply ignored and tests for @a.

Answer 2

Connect the comparator output to a command block with the following command:

/blockdata x y z {SuccessCount:0}

where x, y, and z are the coordinates of the first command block

This happens because the comparator outputs if the command block has ever successfully executed the command. By using the blockdata command, you set the successful-execution-of-command counter of the command block to 0, making the comparator turn off

sorry for my english :(

Answer 3

If you write a wrong command like "testfor @a[asdsfa]" it will be "testfor @a" so it will search all the map and find you so comparator will powered "testfor @a[, , , r=]" try this

Answer 4

Comparators release a small signal to the first piece of redstone connected to it. The repeater is simply amplifying this signal. To fix, just make the repeater and the comparator a block or maybe two apart with redstone in the middle.