diff --git a/Modbus.Net/Modbus.Net.Modbus/Modbus.Net.Modbus.csproj b/Modbus.Net/Modbus.Net.Modbus/Modbus.Net.Modbus.csproj
index 0032869..72489de 100644
--- a/Modbus.Net/Modbus.Net.Modbus/Modbus.Net.Modbus.csproj
+++ b/Modbus.Net/Modbus.Net.Modbus/Modbus.Net.Modbus.csproj
@@ -5,7 +5,7 @@
     <AssemblyName>Modbus.Net.Modbus</AssemblyName>
     <RootNamespace>Modbus.Net.Modbus</RootNamespace>
     <PackageId>Modbus.Net.Modbus</PackageId>
-    <Version>1.3.0</Version>
+    <Version>1.3.1</Version>
     <Authors>Chris L.(Luo Sheng)</Authors>
     <Company>Hangzhou Delian IoT Science Technology Co.,Ltd.</Company>
     <Product>Modbus.Net.Modbus</Product>
diff --git a/Modbus.Net/Modbus.Net.OPC/Modbus.Net.OPC.csproj b/Modbus.Net/Modbus.Net.OPC/Modbus.Net.OPC.csproj
index f730c61..2b73a3f 100644
--- a/Modbus.Net/Modbus.Net.OPC/Modbus.Net.OPC.csproj
+++ b/Modbus.Net/Modbus.Net.OPC/Modbus.Net.OPC.csproj
@@ -5,7 +5,7 @@
     <AssemblyName>Modbus.Net.OPC</AssemblyName>
     <RootNamespace>Modbus.Net.OPC</RootNamespace>
     <PackageId>Modbus.Net.OPC</PackageId>
-    <Version>1.3.0</Version>
+    <Version>1.3.1</Version>
     <Authors>Chris L.(Luo Sheng)</Authors>
     <Company>Hangzhou Delian IoT Science Technology Co.,Ltd.</Company>
     <Description>Modbus.Net OPC Implementation</Description>
diff --git a/Modbus.Net/Modbus.Net.Siemens/Modbus.Net.Siemens.csproj b/Modbus.Net/Modbus.Net.Siemens/Modbus.Net.Siemens.csproj
index c0be4ee..004dd33 100644
--- a/Modbus.Net/Modbus.Net.Siemens/Modbus.Net.Siemens.csproj
+++ b/Modbus.Net/Modbus.Net.Siemens/Modbus.Net.Siemens.csproj
@@ -5,7 +5,7 @@
     <AssemblyName>Modbus.Net.Siemens</AssemblyName>
     <RootNamespace>Modbus.Net.Siemens</RootNamespace>
     <PackageId>Modbus.Net.Siemens</PackageId>
-    <Version>1.3.0</Version>
+    <Version>1.3.1</Version>
     <Authors>Chris L.(Luo Sheng)</Authors>
     <Company>Hangzhou Delian IoT Science Technology Co.,Ltd.</Company>
     <Description>Modbus.Net Siemens Profinet Implementation</Description>
diff --git a/Modbus.Net/Modbus.Net.Standard/Modbus.Net.Standard.csproj b/Modbus.Net/Modbus.Net.Standard/Modbus.Net.Standard.csproj
index 1f55f26..47d410e 100644
--- a/Modbus.Net/Modbus.Net.Standard/Modbus.Net.Standard.csproj
+++ b/Modbus.Net/Modbus.Net.Standard/Modbus.Net.Standard.csproj
@@ -5,7 +5,7 @@
     <AssemblyName>Modbus.Net</AssemblyName>
     <RootNamespace>Modbus.Net</RootNamespace>
     <PackageId>Modbus.Net</PackageId>
-    <Version>1.3.0</Version>
+    <Version>1.3.1</Version>
     <Product>Modbus.Net</Product>
     <Authors>Chris L.(Luo Sheng)</Authors>
     <Company>Hangzhou Delian IoT Science Technology Co.,Ltd.</Company>
diff --git a/Modbus.Net/Modbus.Net/Modbus.Net.csproj b/Modbus.Net/Modbus.Net/Modbus.Net.csproj
index 0ddcdb8..146e8e0 100644
--- a/Modbus.Net/Modbus.Net/Modbus.Net.csproj
+++ b/Modbus.Net/Modbus.Net/Modbus.Net.csproj
@@ -5,7 +5,7 @@
     <AssemblyName>Modbus.Net</AssemblyName>
     <RootNamespace>Modbus.Net</RootNamespace>
     <PackageId>Modbus.Net</PackageId>
-    <Version>1.3.0</Version>
+    <Version>1.3.1</Version>
     <Product>Modbus.Net</Product>
     <Authors>Chris L.(Luo Sheng)</Authors>
     <Company>Hangzhou Delian IoT Science Technology Co.,Ltd.</Company>
diff --git a/Modbus.Net/src/Base.Common/ProtocalUnit.cs b/Modbus.Net/src/Base.Common/ProtocalUnit.cs
index fc9418c..b4a1c93 100644
--- a/Modbus.Net/src/Base.Common/ProtocalUnit.cs
+++ b/Modbus.Net/src/Base.Common/ProtocalUnit.cs
@@ -25,7 +25,7 @@ namespace Modbus.Net
 		/// <param name="message">结构化的输入数据</param>
 		/// <typeparam name="T">IInputStruct的具体类型</typeparam>
 		/// <returns>格式化后的字节流</returns>
-		public byte[] Format<T>(T message) where T : IInputStruct
+		public byte[] Format<T>(T message) where T : class, IInputStruct
 		{
 			return Format(message);
 		}