[1.3] How To Use Modems (Rednet)

rednet.open("right")

rednet.broadcast("Our information")

rednet.open("right") 

id, message  = rednet.receive(10)

print ("Computer ".. id .. " has sent us a message")
print ("The message is")
print (message)

rednet.open("right")
rednet.send(5, "Our Information")

Pizmovc, on 28 February 2012 - 09:10 PM said:

How would I go about doing that? I can't just do x = MyProgram right?

local file = fs.open("Your/file/path", "r")
if file then
    local sFile = file.readAll()
    rednet.send(ID, sFile)
    file.close()
end

local allowedComputerID = 5

local id, msg = rednet.receive(10)
if id == allowedComputerID then
  print( msg )
end

local allowedComputerID = 5

local sEvent, param1, param2 = os.pullEvent()

if sEvent == "rednet_message" and param1 == allowedComputerID then
  print( param2 )
end

rednet.recieve()

Brilliantos, on 01 March 2012 - 02:05 PM said:

Hmm i tried what you said in game and it keeps telling me it is expecting 'then' even though i have put the then in the right place

Brilliantos, on 01 March 2012 - 02:40 PM said:

Its fine i got it working you just forgot the "" around AllowedComputerID :unsure:/>/>

local nAllowedComputerID = 1	-- Change this number to the ID of your sending computer.
local sSide = "back"	-- Change this to the side of your receiving computer, where messages are coming in.

rednet.open( sSide )	-- Open the rednet-port on side 'sSide'
while true do
  local sEvent, param1, param2 = os.pullEvent()	-- Listen for events and two of their parameters.

  if sEvent == "rednet_message" and param1 == nAllowedComputerID then
	print( param2 )
  end

  if sEvent == "char" and param1 == "q" then break end	-- Pressing q stops the program.
end

rednet.close( sSide )	-- Close the rednet-port on side 'sSide'

function os.pullEvent()
local sEvent, param1, param2, event, p1, p2, p3, p4, p5 = os.pullEventRaw()
if event == "terminate" then
os.reboot()
end
if sEvent == "rednet_message" and param1 == 144 and param2 == 54 then
rs.setOutput("bottom", true)
sleep(1)
rs.etOutput("bottom", false)  
end
return event, p1, p2, p3, p4, p5
end
function pass()
term.clear()
term.setCursorPos( 1, 1 )
print ("Base Lockdown disengage system")
print ("Enter Authorisation to unlock and light up")
t = read("*")
write ("> ")
if t == "lettherebelight" then
rs.setOutput("bottom", true)
sleep(1)
rs.setOutput("bottom", false)
pass()
elseif t == "sillypc" then
term.clear()
term.setCursorPos( 1, 1 )
print ("PRROGRAM TERMINATED")
shell.run"shell"
else
pass()
end
end
pass()

remlly, on 03 March 2012 - 03:30 PM said:

ok, can somebody help, if i typ rednet.open('''right'') its says no such program. i have craftos 1.3

remlly, on 03 March 2012 - 03:50 PM said:

i''ll try…
edit, nope. if i typ rednet.open(''back'')'i get :27: [string ''lua'']:1: expected, i dont know waht this means

and the same on the turtle but at the end unexpected symbol

Espen, on 03 March 2012 - 04:09 PM said:

remlly, on 03 March 2012 - 03:50 PM said:

i''ll try…
edit, nope. if i typ rednet.open(''back'')'i get :27: [string ''lua'']:1: expected, i dont know waht this means

and the same on the turtle but at the end unexpected symbol

Ahh, now I see your problem.^^
You're not using double-quotes, but two single-quotes instead.
Use two double-quotes " instead of two single-quotes ''
The former is one character and the latter is two characters.

remlly, on 03 March 2012 - 04:13 PM said:

Espen, on 03 March 2012 - 04:09 PM said:

remlly, on 03 March 2012 - 03:50 PM said:

i''ll try…
edit, nope. if i typ rednet.open(''back'')'i get :27: [string ''lua'']:1: expected, i dont know waht this means

and the same on the turtle but at the end unexpected symbol

Ahh, now I see your problem.^^
You're not using double-quotes, but two single-quotes instead.
Use two double-quotes " instead of two single-quotes ''
The former is one character and the latter is two characters.

youre messing with my brain!!!!! 2 quotes singel quotes, wahts the differnet. is it this '' or this ' or ' '

remlly, on 03 March 2012 - 04:13 PM said:

youre messing with my brain!!!!! 2 quotes singel quotes, wahts the differnet. is it this '' or this ' or ' '

local id, msg = rednet.receive(10)

local id, msg = rednet.receive(10)
if id == 23 then
    print(msg)
end

MysticT, on 03 March 2012 - 05:49 PM said:

rednet.receive() returns 2 values, sender ID and the message.
You have to save those values in variables, something like this:

local id, msg = rednet.receive(10)

If you want to receive from a particular id, you receive the messages and then check the sender id. (I suppose you wanted to do that)
A simple example:

local id, msg = rednet.receive(10)
if id == 23 then
	print(msg)
end

print ("Computer ".. id .. " has sent us a message")
print ("The message is")
print (message)

print ("Computer ".. id .. " has sent us a message\n", "The message is\n", message);

ENET, on 06 March 2012 - 11:45 PM said:

The print takes indefinite amount of args.

print ("Computer ".. id .. " has sent us a message")
print ("The message is")
print (message)

Can be….

print ("Computer ".. id .. " has sent us a message\n", "The message is\n", message);

And it will make less calls to the lua parser.

print ("Computer ", id, " has sent us a message\n", "The message is\n", message)

function print( ... )
 local nLinesPrinted = 0
 for n,v in ipairs( { ... } ) do
  nLinesPrinted = nLinesPrinted + write( tostring( v ) )
 end
 nLinesPrinted = nLinesPrinted + write( "\n" )
 return nLinesPrinted
end

mayaman79, on 08 March 2012 - 01:28 AM said:

A quick question:

Is there a way to decide how long he will broadcast?

local id, message = rednet.receive(10)

local id, message = rednet.receive()

Sides = {"back","right","left","front","top","bottom"}
for i=1,#Sides do
if peripheral.isPresent(Sides[i]) then
  if peripheral.getType(Sides[i]) == "modem" then
   side = Sides[i]
  end
end
end

if side == nil then
  print("This computer has no modem.")
end

pieiscool32, on 10 March 2012 - 04:12 PM said:

ok, thanks, i wasn't looking for typos, whoops…

EDIT: i went to look at the client and i set up line 5 like this: "local 2, message = rednet.receive(10)" and now it says it needs a <Name>… what name?

local id, msg = rednet.receive()

local popcorn, fireworks = rednet.receive()

local id, msg = rednet.receive()
if id == 5 then
  print( "Message from #"..id..": "..msg )
end

Message from #5: Tomatoes are red.

while true do
rednet.open("right")
msg = rednet.receive(10)
print(msg)
end

id,msg = rednet.receive(10)

pieiscool32, on 11 March 2012 - 06:49 PM said:

ok, when i send my client a message using this code

while true do
rednet.open("right")
msg = rednet.receive(10)
print(msg)
end

and any message that i send it looks like this:

>msg


7

("7" is the # of the comp i am sending it from)
what is wrong here, and i made more complicated code that does about the same, it doesn't read the message properly.

local id, msg = rednet.receive()

local msg = rednet.receive()

pieiscool32, on 11 March 2012 - 06:49 PM said:

ok, when i send my client a message using this code

 while true do rednet.open("right") msg = rednet.receive(10) print(msg) end 

and any message that i send it looks like this: >msg 7 ("7" is the # of the comp i am sending it from) what is wrong here, and i made more complicated code that does about the same, it doesn't read the message properly.

Liraal, on 11 March 2012 - 07:20 PM said:

_,message=rednet.receive()

pieiscool32, on 11 March 2012 - 07:14 PM said:

ok, but then how do i make it so a program reads the message but not the id of the compuer?

firstResult, secondResult, thirdResult = x()

secondResult = x()

firstResult, secondResult = x()

_, secondResult = x()

3istee, on 11 March 2012 - 06:56 PM said:

"rednet.receive"
has two Arguments.

ironsmith123, on 14 March 2012 - 11:38 PM said:

Okay, so I get it now, but how would i send a command such as "tunnel 80"?

local id, cmd = rednet.receive(10)
if cmd == nil then
print("Time out.")
elseif cmd == "lumberjack" then
shell.run("lumberjack")
else
print("compy "..id..": "..cmd)
end

jmcneely, on 14 March 2012 - 08:03 PM said:

Is there anyway to get the label of a computer using the received ID number?

ironsmith123, on 15 March 2012 - 04:59 AM said:

jmcneely, on 14 March 2012 - 08:03 PM said:

Is there anyway to get the label of a computer using the received ID number?

I believe to find the ID of the computer or turtle just type id and it gives you that id. Btw, I'd be happy to whitelist you on my cc server I have set up. The address is 24.237.251.57:25566
Please tell me ur mc ign so I can whitelist you of your interested. :D/>/>

6677, on 15 March 2012 - 08:56 AM said:

ironsmith123, on 15 March 2012 - 04:59 AM said:

jmcneely, on 14 March 2012 - 08:03 PM said:

Is there anyway to get the label of a computer using the received ID number?

I believe to find the ID of the computer or turtle just type id and it gives you that id. Btw, I'd be happy to whitelist you on my cc server I have set up. The address is 24.237.251.57:25566
Please tell me ur mc ign so I can whitelist you of your interested. :D/>/>

He wanted the ID of another computer.

The answer, you can't directly although you could keep a list locally of what id has what label and then do a local comparison. You could also send a message "GET_ID" to that computer and have it return its label to update your local list.

ironsmith123, on 15 March 2012 - 06:06 PM said:

So does anyone know how to send commands such as "tunnel 80" to a turtle over rednet?

Muud12, on 15 March 2012 - 06:52 PM said:

Make this is impossible

6677, on 15 March 2012 - 08:56 AM said:

He wanted the ID of another computer.

The answer, you can't directly although you could keep a list locally of what id has what label and then do a local comparison. You could also send a message "GET_ID" to that computer and have it return its label to update your local list.

shell.run(program.." "..param)

print ("what is the program?")
local program = io.read()
print("what is the parameter?")
local param = io.read()

print("What side is your modem on?")
local side = io.read() --Find the side of the PC with the Modem
rednet.open(side)

term.write("Info to send:")
info = io.read() --Gather the info to send

print("What ID is your Turtle?")
local TurtID = io.read() --Find the ID of the receiving Turtle

TurtID = tonumber(TurtID)
rednet.send(TurtID, info) -- Send the info

rednet.open("right")
message = "Blank"
id = 0
while message == "Blank" do --keep looking for info until received
     id, message = rednet.receive(10)
end
if message ~= "Blank" then
     print("Incoming Info From PC #",id)
     print("Info:")
     print(message)
end

qwerty6543, on 01 April 2012 - 04:12 PM said:

I went in to lua and typed rednet.send(39, "Hello") to a computer that was listening with open modems but all it did was put the listening computer out of listening mode. I tried it like 10 time but no avail. help!

qwerty6543, on 07 April 2012 - 12:34 AM said:

qwerty6543, on 01 April 2012 - 04:12 PM said:

I went in to lua and typed rednet.send(39, "Hello") to a computer that was listening with open modems but all it did was put the listening computer out of listening mode. I tried it like 10 time but no avail. help!

Never Mind, i found out i did ot do the print(message) thing.

strideynet, on 11 April 2012 - 07:38 AM said:

Espen have you seen project netblock is general discussion
If you,interested you can join it as you have alot of knolledge!

Elite, on 27 June 2012 - 07:46 PM said:

Is there any program that would allow me to broadcast/send from upto more than 50 blocks using a computer halfway? Say I want to broadcast something 100 blocks away. I place a computer 50 blocks away. This way its perfectly inbetween the receiving and sending side. Is there a program that could forward the message to the next computer?

rednet:350: string expected

iniciando
recibiendo
rednet:350: string expected

function compConex()
term.clear()
borde()
term.setCursorPos(3,17)
write("Intentando conectar con cliente...")
rednet.open("right")
rednet.broadcast("ping")
id, rUserName = rednet.receive(10)
term.setCursorPos(3,17)
term.clearLine()

if rUserName == nil then
  term.setCursorPos(3,17)
  term.clearLine()
  write ("No ha sido posible establecer una conexión")
  bRedNet = false
  sleep(4)
else
  write("Comprobando nombre de usuario...")
end

if rUserName ~= UserName then
  term.setCursorPos(3,17)
  term.clearLine()
  write ("Nombre de usuario incorrecto")
  bRedNet = false
  sleep(4)
elseif rUserName == UserName then
  term.setCursorPos(3,17)
  term.clearLine()
  write("Comprobando contraseña...")
  id, rPassword = rednet.receive(10)
  if rPassword == Password then
   term.setCursorPos(3,17)
   term.clearLine()
   write("Conectado correctamente")
   bRedNet = true
   --guardar id
   sleep(4)
  else
   bRedNet = false
   term.setCursorPos(3,17)
   term.clearLine()
   write ("Contraseña incorrecta")
   sleep(4)
  end
end
end
print ("user")
UserName = io.read()
print ("pass")
Password = io.read()
compConex()

UserName = "testname"
UserName = "testpass"
message = "blank"
while true do
print ("iniciando")
rednet.open("right")
id, message = rednet.receive()
print ("recibiendo")
if message == "ping" then
  rednet.send(id, UserName)
  sleep(2)
  rednet.send(id, Password)
end
end

Appleeater, on 25 January 2013 - 05:56 AM said:

This is nice, how could I use this to send files and revive files?

local readFile = fs.open("<filename>", "r")
local fileTab = {}
repeat
  table.insert(fileTab, readFile.readLine())
until readFile.readLine() == nil
readFile.close()

rednet.open("<side>")
rednet.send(<ID>, textutils.serialize(fileTab))
rednet.close()

rednet.open("<SIDE>")
local id, msg, dist = rednet.receive()
local contents = textutils.unserialize(msg)
local saveFile = fs.open("<FILENAME>", "w")
for i = 1, #contents do
  saveFile.writeLine(contents[i])
end
saveFile.close()

Cranium, on 25 January 2013 - 08:57 AM said:

Appleeater, on 25 January 2013 - 05:56 AM said:

This is nice, how could I use this to send files and revive files?

You can read the file, then put it into a string, then send it over rednet. Somethign like this:

local readFile = fs.open("<filename>", "r")
local fileTab = {}
repeat
  table.insert(fileTab, readFile.readLine())
until readFile.readLine() == nil
readFile.close()

rednet.open("<side>")
rednet.send(<ID>, textutils.serialize(fileTab))
rednet.close()

That will send the file in a table, line by line.

rednet.open("<SIDE>")
local id, msg, dist = rednet.receive()
local contents = textutils.unserialize(msg)
local saveFile = fs.open("<FILENAME>", "w")
for i = 1, #contents do
  saveFile.writeLine(contents[i])
end
saveFile.close()

That should receive the file and save it.

UnicornForrest, on 09 February 2013 - 07:24 AM said:

Im trying to write a program to send and receive messages, but its not working.
Im trying to use local id = read() to save what number you type for the computer id youre sending to, but when i do
rednet.send("..id..","..msg..") it says the id needs to be a positive number. I know that this should replace id with the number, but it doesnt work.

Herû, on 09 February 2013 - 10:37 AM said:

UnicornForrest, on 09 February 2013 - 07:24 AM said:

Im trying to write a program to send and receive messages, but its not working.
Im trying to use local id = read() to save what number you type for the computer id youre sending to, but when i do
rednet.send("..id..","..msg..") it says the id needs to be a positive number. I know that this should replace id with the number, but it doesnt work.

If you use rednet.send("..id..","..msg..") and id is 3 and msg is "Hello world!", you will send the message "..msg.." To computerid "..id.." and not the message "Hello world!" To computerid 3 (remember how you shall define variables (" shall not be used))

Use rednet.send(id,msg) (you do not need .. If you do not shall have both plain text and variables together).

os.pullEvent = os.pullEventRaw
term.clear()
term.setCursorPos(1,1)
rednet.open("top")
print("Broadcast or personal message?")
input = read()
if input == "broadcast" then
 term.clear()
 term.setCursorPos(1,1)
 write("Message:")
 local msg = read()
 rednet.broadcast("'..msg..'")
 print("Sent")
 sleep(2)
 os.reboot()
elseif input == "personal" then
 term.clear()
 term.setCursorPos(1,1)
 write("To:")
 local id = read()
 write("Message:")
 local msg = read()
 rednet.send(id,msg)
 print("Sent")
 sleep(2)
 os.reboot()
end

UnicornForrest, on 09 February 2013 - 12:07 PM said:

–snip–

local oldPull = os.pullEvent
os.pullEvent = os.pullEventRaw
term.clear()
term.setCursorPos(1,1)
rednet.open("top")
print("Broadcast or personal message?")
local input = read()
if input == "broadcast" then
term.clear()
term.setCursorPos(1,1)
write("Message:")
local msg = read()
rednet.broadcast(msg)
print("Sent")
sleep(2)
os.reboot()
elseif input == "personal" then
while true do
term.clear()
term.setCursorPos(1,1)
write("To:")
local id = tonumber(read())
if id ~= nil then break end
print("ID must be a number.")
sleep(1)
end
write("Message:")
local msg = read()
rednet.send(id,msg)
print("Sent")
sleep(2)
os.reboot()
end

MudkipTheEpic, on 09 February 2013 - 03:31 PM said:

UnicornForrest, on 09 February 2013 - 12:07 PM said:

–snip–

You were not making the ID a number, so here is the correct code.

Spoiler

local oldPull = os.pullEvent
os.pullEvent = os.pullEventRaw
term.clear()
term.setCursorPos(1,1)
rednet.open("top")
print("Broadcast or personal message?")
local input = read()
if input == "broadcast" then
term.clear()
term.setCursorPos(1,1)
write("Message:")
local msg = read()
rednet.broadcast(msg)
print("Sent")
sleep(2)
os.reboot()
elseif input == "personal" then
while true do
term.clear()
term.setCursorPos(1,1)
write("To:")
local id = tonumber(read())
if id ~= nil then break end
print("ID must be a number.")
sleep(1)
end
write("Message:")
local msg = read()
rednet.send(id,msg)
print("Sent")
sleep(2)
os.reboot()
end

Doyle3694, on 14 February 2013 - 11:39 PM said:

Casper/ anyone who can edit, maybe add a note on top of the tutorial that this is not how modems work anymore?