added float helper doc

lib/float.ex

@@ -1,25 +1,76 @@
 defmodule Modbus.IEEE754 do
+  @moduledoc """
+  IEEE754 float helper
 
+  Based on https://www.h-schmidt.net/FloatConverter/IEEE754.html.
+  """
+
+  @doc """
+  Converts a couple of 16-bit registers to IEEE754 float.
+
+  ## Example
+
+  ```elixir
+  +5.0 = IEEE754.from_2_regs(0x40a0, 0x0000)
+  ```
+  """
   def from_2_regs(w0, w1) do
     <<value::float-32>> = <<w0::16, w1::16>>
     value
   end
 
+  @doc """
+  Converts a couple of 16-bit registers to IEEE754 float.
+
+  ## Example
+
+  ```elixir
+  +5.0 = IEEE754.from_2_regs(0x40a0, 0x0000)
+  ```
+  """
   def from_2_regs([w0, w1]) do
     <<f::float-32>> = <<w0::16, w1::16>>
     f
   end
 
+
+  @doc """
+  Converts a list of 2n 16-bit registers to a IEEE754 floats list.
+
+  ## Example
+
+  ```elixir
+  [-5.0, +5.0] = IEEE754.from_2n_regs([0xc0a0, 0x0000, 0x40a0, 0x0000])
+  ```
+  """
   def from_2n_regs([]), do: []
   def from_2n_regs([w0, w1 | tail]) do
     [from_2_regs(w0, w1) | from_2n_regs(tail)]
   end
 
+  @doc """
+  Converts a IEEE754 float to a couple of 16-bit registers.
+
+  ## Example
+
+  ```elixir
+  [0xc0a0, 0x0000] = IEEE754.to_2_regs(-5.0)
+  ```
+  """
   def to_2_regs(f) do
     <<w0::16, w1::16>> = <<f::float-32>>
     [w0, w1]
   end
 
+  @doc """
+  Converts a list of IEEE754 floats to a list of 2n 16-bit registers.
+
+  ## Example
+
+  ```elixir
+  [0xc0a0, 0x0000, 0x40a0, 0x0000] = IEEE754.to_2n_regs([-5.0, +5.0])
+  ```
+  """
   def to_2n_regs([]), do: []
   def to_2n_regs([f | tail]) do
     [w0, w1] = to_2_regs(f)

lib/master.ex

@@ -5,6 +5,7 @@ defmodule Modbus.Tcp.Master do
   ## Example
 
   ```elixir
+  #run with: mix opto22
   alias Modbus.Tcp.Master
 
   # opto22 rack configured as follows
@@ -34,10 +35,15 @@ defmodule Modbus.Tcp.Master do
   #alternate m1.p2 and m1.p3
   :ok = Master.exec(pid, {:fc, 1, 6, [1, 0]})
 
+  #https://www.h-schmidt.net/FloatConverter/IEEE754.html
   #write -5V (IEEE 754 float) to m3.p0
+  #<<-5::float-32>> -> <<192, 160, 0, 0>>
   :ok = Master.exec(pid, {:phr, 1, 24, [0xc0a0, 0x0000]})
+  :ok = Master.exec(pid, {:phr, 1, 24, Modbus.IEEE754.to_2_regs(-5.0)})
   #write +5V (IEEE 754 float) to m3.p1
+  #<<+5::float-32>> -> <<64, 160, 0, 0>>
   :ok = Master.exec(pid, {:phr, 1, 26, [0x40a0, 0x0000]})
+  :ok = Master.exec(pid, {:phr, 1, 26, Modbus.IEEE754.to_2_regs(+5.0)})
 
   :timer.sleep(20) #outputs settle delay
 
@@ -46,6 +52,8 @@ defmodule Modbus.Tcp.Master do
 
   #read previous analog channels as input registers
   {:ok, [0xc0a0, 0x0000, 0x40a0, 0x0000]} = Master.exec(pid, {:rir, 1, 24, 4})
+  {:ok, data} = Master.exec(pid, {:rir, 1, 24, 4})
+  [-5.0, +5.0] = Modbus.IEEE754.from_2n_regs(data)
   ```
   """
   alias Modbus.Tcp
@@ -71,7 +79,6 @@ defmodule Modbus.Tcp.Master do
   ```elixir
   Modbus.Tcp.Master.start_link([ip: {10,77,0,2}, port: 502, timeout: 2000])
   ```
-
   """
   def start_link(params, opts \\ []) do
     Agent.start_link(fn -> init(params) end, opts)

lib/shared.ex

@@ -1,4 +1,5 @@
 defmodule Modbus.Model.Shared do
+  @moduledoc false
   alias Modbus.Model
 
   def start_link(params, opts \\ []) do