peripheral

Peripherals are blocks (or turtle and pocket computer upgrades) which can be controlled by a computer. For instance, the speaker peripheral allows a computer to play music and the monitor peripheral allows you to display text in the world.

Referencing peripherals

Computers can interact with adjacent peripherals. Each peripheral is given a name based on which direction it is in. For instance, a disk drive below your computer will be called "bottom" in your Lua code, one to the left called "left" , and so on for all 6 directions ("bottom", "top", "left", "right", "front", "back").

You can list the names of all peripherals with the peripherals program, or the peripheral.getNames function.

It's also possible to use peripherals which are further away from your computer through the use of Wired Modems. Place one modem against your computer, run Networking Cable to your peripheral, and then place another modem against that block. You can then right click the modem to use (or attach) the peripheral. This will print a peripheral name to chat, which can then be used just like a direction name to access the peripheral. You can click on the message to copy the name to your clipboard.

Using peripherals

Once you have the name of a peripheral, you can call functions on it using the peripheral.call function. This takes the name of our peripheral, the name of the function we want to call, and then its arguments.

Let's say we have a monitor above our computer (and so "top") and want to write some text to it. We'd write the following:

peripheral.call("top", "write", "This is displayed on a monitor!")

Once you start calling making a couple of peripheral calls this can get very repetitive, and so we can wrap a peripheral. This builds a table of all the peripheral's functions so you can use it like an API or module.

For instance, we could have written the above example as follows:

local my_monitor = peripheral.wrap("top")
my_monitor.write("This is displayed on a monitor!")

Finding peripherals

Sometimes when you're writing a program you don't care what a peripheral is called, you just need to know it's there. For instance, if you're writing a music player, you just need a speaker - it doesn't matter if it's above or below the computer.

Thankfully there's a quick way to do this: peripheral.find. This takes a peripheral type and returns all the attached peripherals which are of this type.

What is a peripheral type though? This is a string which describes what a peripheral is, and so what functions are available on it. For instance, speakers are just called "speaker", and monitors "monitor". Some peripherals might have more than one type - a Minecraft chest is both a "minecraft:chest" and "inventory".

You can get all the types a peripheral has with peripheral.getType, and check a peripheral is a specific type with peripheral.hasType.

To return to our original example, let's use peripheral.find to find an attached speaker:

local speaker = peripheral.find("speaker")
speaker.playNote("harp")

See also

• peripheral This event is fired whenever a new peripheral is attached.
• peripheral_detach This event is fired whenever a peripheral is detached.

Changes

• New in version 1.3
• Changed in version 1.51: Add support for wired modems.
• Changed in version 1.99: Peripherals can have multiple types.

getNames()Source

Provides a list of all peripherals available.

If a device is located directly next to the system, then its name will be listed as the side it is attached to. If a device is attached via a Wired Modem, then it'll be reported according to its name on the wired network.

Returns

1. { string... } A list of the names of all attached peripherals.

Changes

• New in version 1.51

isPresent(name)Source

Determines if a peripheral is present with the given name.

Parameters

1. name string The side or network name that you want to check.

Returns

1. boolean If a peripheral is present with the given name.

Usage

• peripheral.isPresent("top")

• peripheral.isPresent("monitor_0")

getType(peripheral)Source

Get the types of a named or wrapped peripheral.

Parameters

1. peripheral string | table The name of the peripheral to find, or a wrapped peripheral instance.

Returns

1. string... The peripheral's types, or nil if it is not present.

Usage

• Get the type of a peripheral above this computer.

  peripheral.getType("top")
  

Changes

• Changed in version 1.88.0: Accepts a wrapped peripheral as an argument.
• Changed in version 1.99: Now returns multiple types.

hasType(peripheral, peripheral_type)Source

Check if a peripheral is of a particular type.

Parameters

1. peripheral string | table The name of the peripheral or a wrapped peripheral instance.
2. peripheral_type string The type to check.

Returns

1. boolean | nil If a peripheral has a particular type, or nil if it is not present.

Changes

• New in version 1.99

getMethods(name)Source

Get all available methods for the peripheral with the given name.

Parameters

1. name string The name of the peripheral to find.

Returns

1. { string... } | nil A list of methods provided by this peripheral, or nil if it is not present.

getName(peripheral)Source

Get the name of a peripheral wrapped with peripheral.wrap.

Parameters

1. peripheral table The peripheral to get the name of.

Returns

1. string The name of the given peripheral.

Changes

• New in version 1.88.0

call(name, method, ...)Source

Call a method on the peripheral with the given name.

Parameters

1. name string The name of the peripheral to invoke the method on.
2. method string The name of the method
3. ... Additional arguments to pass to the method

Returns

1. The return values of the peripheral method.

Usage

• Open the modem on the top of this computer.

  peripheral.call("top", "open", 1)
  

wrap(name)Source

Get a table containing all functions available on a peripheral. These can then be called instead of using peripheral.call every time.

Parameters

1. name string The name of the peripheral to wrap.

Returns

1. table | nil The table containing the peripheral's methods, or nil if there is no peripheral present with the given name.

Usage

• Open the modem on the top of this computer.

  local modem = peripheral.wrap("top")
  modem.open(1)
  

find(ty [, filter])Source

Find all peripherals of a specific type, and return the wrapped peripherals.

Parameters

1. ty string The type of peripheral to look for.
2. filter? function(name: string, wrapped: table):boolean A filter function, which takes the peripheral's name and wrapped table and returns if it should be included in the result.

Returns

1. table... 0 or more wrapped peripherals matching the given filters.

Usage

• Find all monitors and store them in a table, writing "Hello" on each one.

  local monitors = { peripheral.find("monitor") }
  for _, monitor in pairs(monitors) do
    monitor.write("Hello")
  end
  

• Find all wireless modems connected to this computer.

  local modems = { peripheral.find("modem", function(name, modem)
      return modem.isWireless() -- Check this modem is wireless.
  end) }
  

• This abuses the filter argument to call rednet.open on every modem.

  peripheral.find("modem", rednet.open)
  

Changes

• New in version 1.6