tracker.lua

CHANNEL_TRACKER = 65531

local modem = peripheral.find("modem")

modem.open(CHANNEL_TRACKER)

while true do
    local event, side, channel, replyChannel, message, distance = os.pullEvent("modem_message")
    if type(message) == "table" and message.dimmension and message.position then
        print(textutils.serialise(message))
    end
end