diff --git a/Modbus.Net/Modbus.Net.Modbus/Modbus.Net.Modbus.csproj b/Modbus.Net/Modbus.Net.Modbus/Modbus.Net.Modbus.csproj
index 7ec1381..b13750b 100644
--- a/Modbus.Net/Modbus.Net.Modbus/Modbus.Net.Modbus.csproj
+++ b/Modbus.Net/Modbus.Net.Modbus/Modbus.Net.Modbus.csproj
@@ -65,6 +65,7 @@
     <None Include="Modbus.Net.Modbus.nuspec">
       <SubType>Designer</SubType>
     </None>
+    <None Include="README.md" />
   </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
diff --git a/Modbus.Net/Modbus.Net.Modbus/README.md b/Modbus.Net/Modbus.Net.Modbus/README.md
new file mode 100644
index 0000000..a1f1617
--- /dev/null
+++ b/Modbus.Net/Modbus.Net.Modbus/README.md
@@ -0,0 +1,80 @@
+Modbus.Net
+===================
+[![NuGet](https://img.shields.io/nuget/v/Modbus.Net.Modbus.svg)](https://www.nuget.org/packages/Modbus.Net.Modbus/)
+
+Modbus Implementation of Modbus.Net
+
+Table of Content:
+* [Basic Concept](#basic)
+* [Address Mapping](#address)
+* [Addres Coding](#coding)
+* [SubAddress Rules](#subpos)
+
+##<a name="basic"></a> Basic Concept
+
+Modbus is a serial communications protocol originally published by Modicon (now Schneider Electric) in 1979 for use with its programmable logic controllers (PLCs). Simple and robust, it has since become a de facto standard communication protocol, and it is now a commonly available means of connecting industrial electronic devices.(From Wekipedia)
+
+##<a name="address"></a> Address Mapping
+
+Modbus has four types of address: Coil, Discrete Input, Holding Register and Input Register.
+
+Modbus has two address description method: standard and extend.
+
+The following table could show the full address discription in Modbus.
+
+Type             | Standard    | Extend        |
+---------------- | ----------- | ------------- |
+Coil             | 00001-09999 | 000001-065536 |
+Discrete Input   | 10001-19999 | 100001-165536 |
+Holding Register | 30001-39999 | 300001-365536 |
+Input Register   | 40001-49999 | 400001-465536 |
+
+Standard and Extend address description are all supported in Modbus.Net.Modbus. The only difference is don't write too large number in address. 
+
+The following table shows how to write address in Modbus.Net.Modbus
+
+Standard Modbus Address | Modbus.Net.Modbus String Address |
+----------------------- | -------------------------------- |
+00001                   | 0X 1                             |
+00002                   | 0X 2                             |
+09999                   | 0X 9999                          |
+065536                  | 0X 65536                         |
+10001                   | 1X 1                             |
+30001                   | 3X 1                             |
+40001                   | 4X 1                             |
+
+##<a name="coding"></a> Address Coding
+
+In Modbus.Net, you can write "0X"(Coil), "1X"(Discrete Input), "3X"(Input Register), "4X"(Holding Register) in Area.
+
+Don't forget to type a space between Area and Address.
+
+If you want to use subpos, type string address like this: 
+
+4X 1.12 (Area Address.Subpos)
+
+##<a name="subpos"></a> SubAddress Rules
+
+For 0X and 1X, the scalation is 1/8. This means each address is bool.
+
+Noticing that you can only read 1X.
+
+SubAddress System is not activated in 0X and 1X.
+
+For 3X and 4X, the scalation is 2. This meas each address is short.
+
+The number of SubAddress is from 0 to 15.
+
+Caution: Modbus.Net.Modbus SubAddress has a giant difference towards standard Modbus.
+
+Bit position from standard modbus is from last to first. But Modbus.Net is from first to last.
+
+Standard Modbus
+
+1  0  1  1  1  0  0  0  1  0  0  0  0  1  1  0
+16 15 14 13 12 11 10 9  8  7  6  5  4  3  2  1
+
+Modbus.Net.Modbus
+
+1  0  1  1  1  0  0  0  1  0  0  0  0  1  1  0
+0  1  2  3  4  5  6  7  8  9  10 11 12 13 14 15
\ No newline at end of file
diff --git a/Modbus.Net/Modbus.Net/README.md b/Modbus.Net/Modbus.Net/README.md
index c9bf971..8de139b 100644
--- a/Modbus.Net/Modbus.Net/README.md
+++ b/Modbus.Net/Modbus.Net/README.md
@@ -11,6 +11,7 @@ Table of Content:
 * [Quick Start](#quick_start)
 * [Tutorial](#tutorial)
 * [Implement](#implement)
+* [Addition](#addition)
 
 ##<a name="features"></a> Features
 * A open platform that you can easy to extend a industrial communication protocal.
@@ -499,7 +500,7 @@ public class AddressFormaterModbus : AddressFormater
 }
 ```
 
-##Addition
+##<a name="addition"></a> Addition
 
 ###For Subpos System
 Subpos system is implemented for reading and writing of bits.
@@ -521,6 +522,8 @@ For example if you want the get a value from the 6th byte in Hold Register. In t
 ```
 Modbus 400003 2nd byte 
 
+Donnot wonder I use real number to implement subpos counter. There are no tolerances because only (1/2 pow n) could be used to count subpos.
+
 ==
 
 class AddressUnit
@@ -551,7 +554,6 @@ Remember subpos system cannot cross a byte in current version. If you want to cr
 * Address Utility (In Road)
 * Move SlaveAddress parameter to GetData and SetData. (In Road)
 * More functions in TaskManager. (In Road)
-* Fix reverse bit bug in Modbus. (In Road)
 
 ###Version 1.2.3
 * OPC UA Support (In Road)
@@ -563,4 +565,4 @@ Remember subpos system cannot cross a byte in current version. If you want to cr
 * Siemens MPI Support (In Road)
 
 ###Version 1.4.0
-* .NET Core Support (Undetermined)
+* .NET Core Support (In Road)