ComputerCraft Wiki - User contributions [en]

Wireless Modem

2013-03-30T07:50:47Z

Kingdaro: Changed the wireless modem recipe. I'm /pretty/ sure this is right, but if it isn't please correct.

{{NeedsWork|The behaviour of Rednet has changed as of 1.5 - please consider updating this page with information. (Please don't add prerelease info!)}}
:''This page is for the Modem blocks. For the modem API, see [[Modem_(API)|Modem (API)]]''
{{Block
|name=Modem
|image=WirelessModem.png
|id=4094
|damage-value=1
|is-peripheral=Yes
|peripheral-api=Modem (API)
}}
Modems are blocks which can be used to wirelessly transfer data between [[Computer|computers]] and [[Turtle|turtles]], using the [[Rednet_(API)|Rednet API]] or the [[Modem_(API)|Modem API]].
To place a modem on a side of a computer, right-click to place the modem while sneaking.

It is also possible to turn the modem on and off by typing "rednet.open ( side )" to open and "rednet.close ( side )" to close.

Modems can send messages to other modems located up to 64 meters away, or 16 meters during a thunderstorm.
As of 1.4 Modem range is increased with higher altitudes. If there is no thunderstorm, the range will always be higher than 64, and at max altitude you would have a range of 384 meters.

In 1.4 and 1.41 there is a miscalculation that causes the range to only be 381 meters at max altitude.

== Recipe ==
{{Crafting grid
|A1=stone |B1=stone |C1=stone
|A2=stone |B2=ender_pearl |C2=stone
|A3=stone |B3=stone |C3=stone
|Output=Modem
}}

== Example (Rednet API)==
* Place 2 computers and add modems to them by clicking the right mouse button while sneaking.
* Access them, and start Lua.
* Once Lua has started, type "[[rednet_(API)|rednet]].[[rednet.open|open]] ("<relative location to modem, e.g. left, right>")" on both computers.
* Check if there exists a connection: a dim, red light should be found on the modem.
* Type on one computer "[[rednet_(API)|rednet]].[[rednet.receive|receive]] (60)". This will make the computer freeze for 60 seconds, or until it has received a signal from the other computers.
* Now, type "[[rednet_(API)|rednet]].[[rednet.broadcast|broadcast]] ('<your message>')" on the other computer. This should send your message to all computers connected.
* Opening the first computer should show the message written on the second computer.

==Modem as a Peripheral==
To use a Modem as a peripheral, you need to either call a method directly using [[peripheral.call]](), or, wrap the modem using the [[Peripheral_(API)|Peripheral API]]. Wrapped modems provide all functions listed in the [[Rednet_(API)|Rednet API]].

For this example, we have a Modem connected to the top of our [[Computer]]:

-- Immediately invoke a method without wrapping
peripheral.call("top", "open")

-- You can also "wrap" the peripheral side to a variable:
local modem = peripheral.wrap("top")
modem.open("top")

[[Category:Peripherals]]

Os.computerID

2012-11-26T10:01:48Z

Kingdaro: dunno where people got "computerID" from, it's "getComputerID"

{{lowercase}}
{{Function
|name=os.getComputerID
|returns=the ID of the Computer
|api=os
|addon=ComputerCraft
|desc=returns the ID of the computer this command is executed on.
|examples=
{{Example
|desc=prints the Computer ID
|code=print(os.getComputerID())
}}
}}

OS (API)

2012-11-26T09:56:11Z

Kingdaro:

The Operating System API allows for interfacing with the Lua based Operating System itself.
{| border="1" cellpadding="2" cellspacing="0"
!style="background:#EEE" width="200px"|Method name
!style="background:#EEE" width="*"|Description
|-
|[[os.version]]()
|Returns the version of the OS the computer is running.
|-
|[[os.getComputerID]]()
|Returns the unique ID of this computer.
|-
|[[os.getComputerLabel]]()
|Returns the label of this computer.
|-
|[[os.setComputerLabel]]( label )
|Set the label of this computer.
|-
|[[os.run]]( environment, programpath, arguments )
|An advanced way of starting programs. A started program will have a given
Environment table which determines what functions it has available, as well as
any variables it will be able to access by default. You may prefer to use the
[[Shell (API)]] unless you need to do something special.
|-
|[[#api|os.loadAPI]]( name )
|Loads a lua script as an API in it's own namespace (see example). It will be available to *all* programs.
-- "apiTest" file
function foo(bar)
print(bar)
end

-- "program" file
apiTest.foo("this is a test")
|-
|[[#api|os.unloadAPI]]( name )
|Unloads a previously loaded API.
|-
|[[Os.pullEvent|os.pullEvent]]( only-event-to-accept )
|Blocks until the computer has detected an event, then returns the event.
|-
|[[#pullEvent|os.pullEventRaw]]()
|Advanced version of pullEvent().
|-
|[[os.queueEvent]]( event, param1, param2, ... )
|Adds an event to the event queue with the name <var>event</var> and the given parameters
|-
|[[os.clock]]()
|Returns CPU time.
|-
|[[os.startTimer]]( timeout )
|Queues an event to be triggered after a number of seconds.
The ID of the timer is returned from this function to differentiate multiple
timers. Timers are one-shot, once they have fired an event you will need to
start another one if you need a recurring timer.
|-
|[[os.sleep]]( timeout )
|Makes the system wait a number of seconds before continuing in the program.
May also be used as simply "sleep( timeout )".
|-
|[[os.time]]()
|Returns the current Minecraft world time.
|-
|[[os.setAlarm]]( time )
|Queues an event to be triggered at the specific Minecraft world time.
|-
|[[os.shutdown]]()
|Turns off the computer.
|-
|[[os.reboot]]()
|Reboots the computer.
|}

== <div id="api">API</div> ==

API are programs which are loaded in to the OS itself, and expose functions
which other programs may use. The stock [[APIs]] that ship with
ComputerCraft are loaded in this way, and may be replaced by a computer's
user or programs.

== <div id="pullEvent">os.pullEvent()</div> ==

os.pullEvent() causes the current program to pause, retrieving the next event
from the computer's queue of events. If there is no event to read, then the
program will stall until such an event becomes available. Note that if a
program has not attempted to pull an event in the past ten seconds, it will
be forcefully terminated to prevent CPU waste in SMP environments.

pullEvent returns the name of the event that was read, as well as up to
five parameters:

<code>
local event, p1, p2, p3, p4, p5 = os.pullEvent()
</code>

os.pullEvent() is usually run inside a 'while true do' loop.

An advanced version of this method <code>os.pullEventRaw</code> bypasses the
normal handling of events from the OS. You may use this to act on the
"Terminate" event (triggered when holding Ctrl-T) for custom termination logic.


[[Category:APIs]]