diff --git a/.iex.exs b/.iex.exs
index c93fe0b..0df3d89 100644
--- a/.iex.exs
+++ b/.iex.exs
@@ -25,11 +25,11 @@ defmodule Helpers do
     Utils.to_hex_string(tag[:epc]) |> String.replace(" ", "")
   end
 
-  def start_async_test(device \\ "/dev/ttyACM0", pulse_width \\ 100, period \\ 500, power \\ 2000) do
+  def start_async_test(device \\ "/dev/ttyACM0", on_time_ms \\ 100, off_time_ms \\ 400, power \\ 2000) do
     Logger.configure(level: :info)
 
     reader =
-      case Reader.start_link(device: device) do
+      case Reader.start_link(device) do
         {:ok, pid} -> pid
         {:error, {:already_started, pid}} -> pid
       end
@@ -37,7 +37,7 @@ defmodule Helpers do
     :ok = Reader.set_read_tx_power(reader, power)
 
     {:ok, listener} = Task.start_link(&print_tags_async/0)
-    Reader.read_async_start(reader, listener, pulse_width, period)
+    Reader.read_async_start(reader, listener, on_time_ms, off_time_ms)
     reader
   end
 
diff --git a/lib/tm_mercury/reader.ex b/lib/tm_mercury/reader.ex
index 91c3e21..b8a1c0d 100644
--- a/lib/tm_mercury/reader.ex
+++ b/lib/tm_mercury/reader.ex
@@ -294,12 +294,12 @@ defmodule TM.Mercury.Reader do
   Start a process and open a connection
   with the reader over UART connected via TTL / USB
 
-  ## Options
-
-  The reader requires the following keys:
+  The reader requires the following parameters:
 
     * `device` - the device file for the reader serial connection.
 
+  ## Optional Parameters
+
   The following keys are optional:
 
     * `speed` - the serial port speed.  Defaults to `115200`.
@@ -327,9 +327,8 @@ defmodule TM.Mercury.Reader do
       * `:max_save`
       * `:sleep`
   """
-  @spec start_link(keyword) :: {:ok, pid} | error
-  def start_link(opts) do
-    device = opts[:device]
+  @spec start_link(String.t, keyword) :: {:ok, pid} | error
+  def start_link(device, opts \\ []) do
     name = Path.basename(device) |> String.to_atom
     GenServer.start_link(__MODULE__, {device, opts}, name: name)
   end
@@ -338,9 +337,9 @@ defmodule TM.Mercury.Reader do
     Logger.debug "Starting RFID reader process for #{device} with pid #{inspect self()}"
 
     # Pass this subset of options along to the transport process
-    ts_opts = Keyword.take(opts, [:device, :speed, :timeout, :framing])
+    ts_opts = Keyword.take(opts, [:speed, :timeout, :framing])
 
-    case Connection.start_link(Transport, {self(), ts_opts}) do
+    case Connection.start_link(Transport, {device, self(), ts_opts}) do
       {:ok, ts} ->
         new_reader = struct(%__MODULE__{}, opts)
 
diff --git a/lib/tm_mercury/transport.ex b/lib/tm_mercury/transport.ex
index 8f178cb..d6c00b5 100644
--- a/lib/tm_mercury/transport.ex
+++ b/lib/tm_mercury/transport.ex
@@ -45,12 +45,12 @@ defmodule TM.Mercury.Transport do
 
   # Connection API
 
-  def init({owner, opts}) do
+  def init({device, owner, opts}) do
     opts = Keyword.merge(@defaults, opts)
     {:ok, uart} = Nerves.UART.start_link
 
     s = %{
-      device: opts[:device],
+      device: device,
       opts: opts,
       uart: uart,
       owner: owner,
diff --git a/test/reader_test.exs b/test/reader_test.exs
index 07a6b7b..1553ecc 100644
--- a/test/reader_test.exs
+++ b/test/reader_test.exs
@@ -4,7 +4,7 @@ defmodule TM.Mercury.ReaderTest do
   alias TM.Mercury.{Reader, SimpleReadPlan, StopTriggerReadPlan}
 
   setup_all do
-    {:ok, pid} = Reader.start_link(device: "/dev/ttyACM0", speed: 115200)
+    {:ok, pid} = Reader.start_link("/dev/ttyACM0", speed: 115200)
     {:ok, %{pid: pid}}
   end