Added stuff.

router.lua

@@ -4,6 +4,26 @@ modem, to act as a routing beacon in conjunction with managed switches.
 ]]--
 local modem = peripheral.wrap("back") or error("Missing modem.")
 
+local STATION_CHANNEL = 1
+
+local function broadcastRoute(route)
+    while true do
+        modem.transmit(0, 42, route)
+        os.sleep(0.5)
+    end
+end
+
+-- Repeats until we are within range of a station that's sending out its info.
+local function waitForStation(stationName)
+    while true do
+        local event, side, channel, replyChannel, msg, dist = os.pullEvent("modem_message")
+        if channel == STATION_CHANNEL and msg == stationName and dist <= 16 then
+            print("Arrived at station " .. stationName)
+            return
+        end
+    end
+end
+
 local args = {...}
 
 local route = args
@@ -12,11 +32,7 @@ for _, branch in pairs(route) do
     print("  "..branch)
 end
 
-local function sendRoute(route)
+parallel.waitForAny(
-    modem.transmit(0, 42, route)
+    function() broadcastRoute(route) end
-end
+    function() waitForStation(route[#route]) end
-
+)
-while true do
-    sendRoute(route)
-    os.sleep(1)
-end

station.lua

@@ -0,0 +1,19 @@
+--[[
+Stations are kiosks where users can configure their portable computer for a
+particular route to another station.
+]]--
+
+local modem = peripheral.wrap("top") or error("Missing top modem")
+local CHANNEL = 1
+local STATION_NAME = "Test Station"
+
+local function broadcastName()
+    while true do
+        modem.transmit(CHANNEL, CHANNEL, STATION_NAME)
+        os.sleep(1)
+    end
+end
+
+parallel.waitForAll(
+    broadcastName
+)

switcher.lua

@@ -1,16 +1,15 @@
 --[[
 This program is to be installed on a computer that controls a single rail
 junction. As a player with a portable computer approaches, that portable
-computer will be sending out a signal indicating their preferred switching
+computer will be sending out a signal containing their route, and this switch
-configuration (the branch they're coming from, and the one they want to go to),
+will decode it and make any adjustments it needs to.
-and the junction's computer will then send a success reply.
 ]]--
 
 local CONFIG_FILE = "switch_config.tbl"
 local CHANNEL = 0
 local config = nil
  
-local modem = peripheral.wrap("top") or error("Missing modem")
+local modem = peripheral.wrap("top") or error("Missing top modem")
 if not modem.isWireless() then error("Wireless modem required") end
 modem.open(CHANNEL)
  
@@ -33,6 +32,7 @@ local function configSetupWizard()
             print("Invalid range value. Should be a positive integer number. Got "..rangeStr)
             return nil
         end
+        cfg.range = rangeInt
     end
     print("How many switch configurations are there? Usually 1 for each possible path of travel.")
     local switchCountStr = io.read()
@@ -103,8 +103,8 @@ local function loadConfig()
         local cfg = textutils.unserialize(f:read("*a"))
         f:close()
         print("Loaded configuration from file:")
-        print("  "..tostring(#config.switches).." switch configurations.")
+        print("  "..tostring(#cfg.switches).." switch configurations.")
-        print("  "..tostring(config.range).." block range.")
+        print("  "..tostring(cfg.range).." block range.")
         return cfg
     else
         print("File "..CONFIG_FILE.." doesn't exist. Start setup wizard? [y/n]")
@@ -156,6 +156,10 @@ end
 -- Handles incoming rail messages that consist of a list of branch names
 -- that the user would like to traverse.
 local function handleModemMsg(replyChannel, msg)
+    if type(msg) == "string" and msg == "PING" then
+        modem.transmit(replyChannel, CHANNEL, "PONG")
+        return
+    end
     -- Ignore invalid messages.
     if not msg or #msg < 2 then return end
     -- Find the switch configuration(s) that pertain to this route.