Difference between revisions of "Rednet.send"

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{{Function
 
{{Function
 
|name=rednet.send
 
|name=rednet.send
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|args={{type|number}} receiverID, {{type|string}} message
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|args={{type|number}} receiverID, {{type|string}} message, [<nowiki/>{{type|string}} protocol]
 
|returns={{Type|boolean}} success code. True if a message has been sent (note - "sent", as opposed to "received" or even "was receivable"), false if not.
 
|returns={{Type|boolean}} success code. True if a message has been sent (note - "sent", as opposed to "received" or even "was receivable"), false if not.
 
|api=rednet
 
|api=rednet
 
|addon=ComputerCraft
 
|addon=ComputerCraft
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|desc=Allows a [[computer]] / [[turtle]] with an attached [[modem]] to send a message intended for a system with a specific ID. At least one such modem must first be "opened" with eg [[Rednet.open|rednet.open()]] before sending is possible. Assuming the target was in range and also had a correctly opened modem, that can then use [[rednet.receive|rednet.receive()]] to collect the message. See also [[rednet.broadcast|rednet.broadcast()]].
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|desc=Allows a [[computer]] / [[turtle]] with an attached [[modem]] to send a message intended for a system with a specific [[os.getComputerID|ID]] (compare [[rednet.broadcast|rednet.broadcast()]], which aims to target everything in range). At least one such modem must first be "[[Rednet.open|opened]]" before sending is possible. Assuming the target was in range and also had a correctly opened modem, it may then use [[rednet.receive|rednet.receive()]] to collect the message.<br><br>
  
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Note that any systems in range (ie, connected to your [[Wired Modem]] network cable runs or close enough to your [[Wireless Modem]]s) are capable of receiving the message if their owners have some idea what ID you're targeting - they need only use [[Modem.open|modem.open()]] to manually open the corresponding channel(s) you're using on their systems, and they have full access to your communications. Use of [[Rednet.open|rednet.open()]] only opens certain channels (selected automatically) - ''this is a "convenience" feature, not a "security" feature.''
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Messages are transmitted on a channel number equal to the target system's ID, with a suggested "reply" channel equal to the sending system's ID. Be aware that if other users are in range of your [[Wireless Modem|wireless]] network, or cabled into your [[Wired Modem|wired]] network, knowing / guessing your target ID number will allow them to [[Modem.open|manually open]] that channel on their own systems in order to receive your messages. As of ComputerCraft 1.6, all rednet messages are additionally sent on channel 65533 (allowing the [[Repeat (program)|repeat script]] to easily detect them).<br><br>
  
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Messages are typically strings, however later versions of ComputerCraft ''(which?)'' may alternatively send tables instead. Those on older versions may find [[Textutils.serialize|textutils.serialize()]] useful when wanting to transmit tables.
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ComputerCraft 1.6 also introduces "[[Rednet (API)#Protocols|protocol]]" - simple string names indicating what the message is about. Receiving systems may filter messages according to their protocols, thereby automatically ignoring incoming messages which don't specify an identical string. It's also possible to [[rednet.lookup|lookup]] which systems in the area are interested in certain protocols, hence making it easier to determine where given messages should be sent in the first place.<br><br>
  
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To get the ID of a given system, refer to [[os.computerID|os.computerID()]].
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Messages are typically strings, however later versions of ComputerCraft ''(which?)'' may alternatively send tables instead. Those users still on older versions may find [[Textutils.serialize|textutils.serialize()]] useful when wanting to transmit tables.
 
|examples=
 
|examples=
 
{{Example
 
{{Example
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|code=rednet.send(22,"ComputerCraft")
 
|code=rednet.send(22,"ComputerCraft")
 
}}
 
}}
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{{Example
 +
|desc=Sends a message to the system with the ID of 22, specifying a protocol of "TestMessages".
 +
|code=rednet.send(22,"ComputerCraft","TestMessages")
 
}}
 
}}
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}}
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{{RednetAPIFunctions}}
  
 
[[Category:API_Functions]]
 
[[Category:API_Functions]]

Revision as of 06:33, 6 June 2014


Grid Redstone.png  Function rednet.send
Allows a computer / turtle with an attached modem to send a message intended for a system with a specific ID (compare rednet.broadcast(), which aims to target everything in range). At least one such modem must first be "opened" before sending is possible. Assuming the target was in range and also had a correctly opened modem, it may then use rednet.receive() to collect the message.

Messages are transmitted on a channel number equal to the target system's ID, with a suggested "reply" channel equal to the sending system's ID. Be aware that if other users are in range of your wireless network, or cabled into your wired network, knowing / guessing your target ID number will allow them to manually open that channel on their own systems in order to receive your messages. As of ComputerCraft 1.6, all rednet messages are additionally sent on channel 65533 (allowing the repeat script to easily detect them).

ComputerCraft 1.6 also introduces "protocol" - simple string names indicating what the message is about. Receiving systems may filter messages according to their protocols, thereby automatically ignoring incoming messages which don't specify an identical string. It's also possible to lookup which systems in the area are interested in certain protocols, hence making it easier to determine where given messages should be sent in the first place.

Messages are typically strings, however later versions of ComputerCraft (which?) may alternatively send tables instead. Those users still on older versions may find textutils.serialize() useful when wanting to transmit tables.
Syntax rednet.send(number receiverID, string message, [string protocol])
Returns boolean success code. True if a message has been sent (note - "sent", as opposed to "received" or even "was receivable"), false if not.
Part of ComputerCraft
API rednet

Examples

Grid paper.png  Example
Sends a message to the system with the ID of 22 (assuming a modem is attached and open).
Code 
rednet.send(22,"ComputerCraft")



Grid paper.png  Example
Sends a message to the system with the ID of 22, specifying a protocol of "TestMessages".
Code 
rednet.send(22,"ComputerCraft","TestMessages")


Grid disk.png Rednet API Functions
rednet.open - rednet.close - rednet.send - rednet.broadcast - rednet.receive - rednet.isOpen - rednet.host - rednet.unhost - rednet.lookup
Retrieved from "https://www.computercraft.info/wiki/index.php?title=Rednet.send&oldid=6581"