This is a simple 3x3 Portcullis/Gate command that only uses one command block to close, and one commend block to open the portcullis/gate.

Although this works for versions 1.12-1.20, some item/block names have changed in different versions, so be sure to check the name for the version you are using. It should autofill when you start typing.

No Need to download the map, just copy and paste the commands into command blocks.
There should be a space between the stacked command blocks (see images).

Commands:
Gate A (faces east>west?)
/fill ~0 ~0 ~4 ~0 ~-2 ~2 air
/fill ~0 ~0 ~4 ~0 ~2 ~2 iron_bars

Gate B (faces north>south?)
/fill ~4 ~0 ~0 ~2 ~-2 ~0 air
/fill ~4 ~0 ~0 ~2 ~2 ~0 fence

Commands confirmed work in Minecraft 1.12.2 to 1.20.
Although only 1.12.2 blocks were used in the downloadable map. Just use the commands on your map with the blocks you want in your version of Minecraft and it will work.

You can swap "iron_bars" with any blocks, but must leave the 'air' alone (can swap to 'water' if underwater).

Note: There are two separate gate commands as one works facing east to west, and the other facing north to south. Try both for your build.
The "air" command opens the gate, the other command uses the block input for the closed gate (i.e: iron_bars).

Why this version?
The map was made in Minecraft version 1.12.2, so they can be used and edited in MC Edit, and used for modded sky worlds, or other modded packs (as mods are always a few versions back).


**Usage Rules**
You use this map for streaming, please link back here then other people can download the map. Feel free to use all or part of any of the buildings in your own worlds or modpacks, just leave a link back here in appreciation and do not re-host the original file.

Enjoy,

Rogue

PS - If having problem's downloading with Drop Box, try one of the following:
1 - on the right side of the screen there are 3 dots that say "More" if you hover over it. Just click and select "Download".
2 - on top the right (next to sign up" there is a down arrow, just click and select "Download".

This is because of something Drop Box has changed at some point (rather then allow direct downloads).