diff --git a/NewLife.Modbus/NewLife.Modbus.csproj b/NewLife.Modbus/NewLife.Modbus.csproj
index 236aeb8..2515c79 100644
--- a/NewLife.Modbus/NewLife.Modbus.csproj
+++ b/NewLife.Modbus/NewLife.Modbus.csproj
@@ -44,6 +44,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
+    <PackageReference Include="NewLife.Core" Version="11.1.2024.1212-beta1042" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/NewLife.Modbus/Protocols/ModbusAsciiMessage.cs b/NewLife.Modbus/Protocols/ModbusAsciiMessage.cs
index 9508675..2848d16 100644
--- a/NewLife.Modbus/Protocols/ModbusAsciiMessage.cs
+++ b/NewLife.Modbus/Protocols/ModbusAsciiMessage.cs
@@ -19,7 +19,7 @@ public class ModbusAsciiMessage : ModbusMessage
     /// <summary>从数据读取消息</summary>
     /// <param name="reader">读取器</param>
     /// <returns></returns>
-    public override Boolean Read(SpanReader reader)
+    public override Boolean Read(ref SpanReader reader)
     {
         var str = reader.ReadString(-1, Encoding.ASCII);
         if (str.Length < 1 + 2 + 2 + 2 || str[0] != ':') return false;
@@ -31,7 +31,7 @@ public override Boolean Read(SpanReader reader)
         var buf = str[1..p].ToHex();
         var reader2 = new SpanReader(buf) { IsLittleEndian = false };
 
-        if (!base.Read(reader2)) return false;
+        if (!base.Read(ref reader2)) return false;
 
         Lrc = buf[^1];
         Lrc2 = ModbusHelper.Lrc(buf, 0, buf.Length - 1);
@@ -47,17 +47,17 @@ public static ModbusAsciiMessage Read(ReadOnlySpan<Byte> data, Boolean reply = f
     {
         var msg = new ModbusAsciiMessage { Reply = reply };
         var reader = new SpanReader(data) { IsLittleEndian = false };
-        return msg.Read(reader) ? msg : null;
+        return msg.Read(ref reader) ? msg : null;
     }
 
     /// <summary>写入消息到数据</summary>
     /// <param name="writer">写入器</param>
     /// <returns></returns>
-    public override Boolean Write(SpanWriter writer)
+    public override Boolean Write(ref SpanWriter writer)
     {
         using var pk = new OwnerPacket(256);
         var writer2 = new SpanWriter(pk.GetSpan()) { IsLittleEndian = false };
-        if (!base.Write(writer2)) return false;
+        if (!base.Write(ref writer2)) return false;
 
         var buf = pk.GetSpan()[..writer2.Position].ToArray();
 
diff --git a/NewLife.Modbus/Protocols/ModbusIpMessage.cs b/NewLife.Modbus/Protocols/ModbusIpMessage.cs
index 5b4785a..6627a17 100644
--- a/NewLife.Modbus/Protocols/ModbusIpMessage.cs
+++ b/NewLife.Modbus/Protocols/ModbusIpMessage.cs
@@ -17,7 +17,7 @@ public class ModbusIpMessage : ModbusMessage
     /// <summary>从数据读取消息</summary>
     /// <param name="reader">读取器</param>
     /// <returns></returns>
-    public override Boolean Read(SpanReader reader)
+    public override Boolean Read(ref SpanReader reader)
     {
         TransactionId = reader.ReadUInt16();
         ProtocolId = reader.ReadUInt16();
@@ -25,7 +25,7 @@ public override Boolean Read(SpanReader reader)
         var len = reader.ReadUInt16();
         if (len < 1 + 1 || len > reader.FreeCapacity) return false;
 
-        return base.Read(reader);
+        return base.Read(ref reader);
     }
 
     /// <summary>从数据读取消息</summary>
@@ -36,13 +36,13 @@ public static ModbusIpMessage Read(ReadOnlySpan<Byte> data, Boolean reply = fals
     {
         var msg = new ModbusIpMessage { Reply = reply };
         var reader = new SpanReader(data) { IsLittleEndian = false };
-        return msg.Read(reader) ? msg : null;
+        return msg.Read(ref reader) ? msg : null;
     }
 
     /// <summary>写入消息到数据</summary>
     /// <param name="writer">写入器</param>
     /// <returns></returns>
-    public override Boolean Write(SpanWriter writer)
+    public override Boolean Write(ref SpanWriter writer)
     {
         writer.Write(TransactionId);
         writer.Write(ProtocolId);
@@ -51,7 +51,7 @@ public override Boolean Write(SpanWriter writer)
         var len = 2 + (pk?.Total ?? 0);
         writer.Write((UInt16)len);
 
-        return base.Write(writer);
+        return base.Write(ref writer);
     }
 
     /// <summary>创建响应</summary>
diff --git a/NewLife.Modbus/Protocols/ModbusMessage.cs b/NewLife.Modbus/Protocols/ModbusMessage.cs
index 1a20486..f650ac2 100644
--- a/NewLife.Modbus/Protocols/ModbusMessage.cs
+++ b/NewLife.Modbus/Protocols/ModbusMessage.cs
@@ -47,7 +47,7 @@ public override String ToString()
     /// <summary>从数据读取消息</summary>
     /// <param name="reader">读取器</param>
     /// <returns></returns>
-    public virtual Boolean Read(SpanReader reader)
+    public virtual Boolean Read(ref SpanReader reader)
     {
         Host = reader.ReadByte();
 
@@ -61,7 +61,8 @@ public virtual Boolean Read(SpanReader reader)
             return true;
         }
 
-        Payload = (ArrayPacket)reader.ReadBytes(-1).ToArray();
+        if (reader.FreeCapacity > 0)
+            Payload = (ArrayPacket)reader.ReadBytes(reader.FreeCapacity).ToArray();
 
         return true;
     }
@@ -72,7 +73,7 @@ public virtual Boolean Read(SpanReader reader)
     public virtual Int32 Read(ReadOnlySpan<Byte> data)
     {
         var reader = new SpanReader(data) { IsLittleEndian = false };
-        if (!Read(reader)) return -1;
+        if (!Read(ref reader)) return -1;
 
         return reader.Position;
     }
@@ -80,7 +81,7 @@ public virtual Int32 Read(ReadOnlySpan<Byte> data)
     /// <summary>写入消息到数据</summary>
     /// <param name="writer">写入器</param>
     /// <returns></returns>
-    public virtual Boolean Write(SpanWriter writer)
+    public virtual Boolean Write(ref SpanWriter writer)
     {
         writer.Write(Host);
 
@@ -107,7 +108,7 @@ public virtual Boolean Write(SpanWriter writer)
     public virtual Int32 Writer(Span<Byte> data)
     {
         var writer = new SpanWriter(data) { IsLittleEndian = false };
-        if (!Write(writer)) return -1;
+        if (!Write(ref writer)) return -1;
 
         return writer.Position;
     }
@@ -118,7 +119,7 @@ public virtual IPacket ToPacket(Int32 bufferSize = 256)
     {
         var pk = new OwnerPacket(bufferSize);
         var writer = new SpanWriter(pk.GetSpan()) { IsLittleEndian = false };
-        if (!Write(writer)) return null;
+        if (!Write(ref writer)) return null;
 
         pk.Resize(writer.Position);
 
diff --git a/NewLife.Modbus/Protocols/ModbusRtuMessage.cs b/NewLife.Modbus/Protocols/ModbusRtuMessage.cs
index f176bb4..bf092b2 100644
--- a/NewLife.Modbus/Protocols/ModbusRtuMessage.cs
+++ b/NewLife.Modbus/Protocols/ModbusRtuMessage.cs
@@ -1,5 +1,7 @@
 using NewLife.Buffers;
 using NewLife.Data;
+using NewLife.Reflection;
+using NewLife.Security;
 
 namespace NewLife.IoT.Protocols;
 
@@ -18,10 +20,10 @@ public class ModbusRtuMessage : ModbusMessage
     /// <summary>从数据读取消息</summary>
     /// <param name="reader">读取器</param>
     /// <returns></returns>
-    public override Boolean Read(SpanReader reader)
+    public override Boolean Read(ref SpanReader reader)
     {
         var p = reader.Position;
-        if (!base.Read(reader)) return false;
+        if (!base.Read(ref reader)) return false;
 
         // 从负载数据里把Crc取出来
         var pk = Payload;
@@ -32,8 +34,12 @@ public override Boolean Read(SpanReader reader)
             Payload = pk.Slice(0, count - 2);
         }
 
-        //reader.Position = p;
-        //Crc2 = ModbusHelper.Crc(stream, (Int32)(stream.Length - stream.Position - 2));
+        // 计算CRC
+        var p2 = reader.Position - 2;
+        var sp = reader.Span.Slice(p, p2 - p);
+        var buf = sp.ToArray();
+
+        Crc2 = Crc16.ComputeModbus(buf, 0, buf.Length);
 
         return true;
     }
@@ -46,16 +52,16 @@ public static ModbusRtuMessage Read(ReadOnlySpan<Byte> data, Boolean reply = fal
     {
         var msg = new ModbusRtuMessage { Reply = reply };
         var reader = new SpanReader(data) { IsLittleEndian = false };
-        return msg.Read(reader) ? msg : null;
+        return msg.Read(ref reader) ? msg : null;
     }
 
     /// <summary>写入消息到数据</summary>
     /// <param name="writer">写入器</param>
     /// <returns></returns>
-    public override Boolean Write(SpanWriter writer)
+    public override Boolean Write(ref SpanWriter writer)
     {
         var p = writer.Position;
-        if (!base.Write(writer)) return false;
+        if (!base.Write(ref writer)) return false;
 
         //writer.Position = p;
         //Crc2 = ModbusHelper.Crc(writer);
diff --git a/Test/Test.csproj b/Test/Test.csproj
index f9b9c0f..4cd49ac 100644
--- a/Test/Test.csproj
+++ b/Test/Test.csproj
@@ -16,7 +16,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="NewLife.Core" Version="11.1.2024.1206" />
+    <PackageReference Include="NewLife.Core" Version="11.1.2024.1212-beta1042" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/WinModbus/WinModbus.csproj b/WinModbus/WinModbus.csproj
index e3c701a..a219ae5 100644
--- a/WinModbus/WinModbus.csproj
+++ b/WinModbus/WinModbus.csproj
@@ -18,7 +18,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="NewLife.Core" Version="11.1.2024.1206" />
+    <PackageReference Include="NewLife.Core" Version="11.1.2024.1212-beta1042" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/XUnitTest/ModbusMessageTests.cs b/XUnitTest/ModbusMessageTests.cs
index 9b32d43..a96246d 100644
--- a/XUnitTest/ModbusMessageTests.cs
+++ b/XUnitTest/ModbusMessageTests.cs
@@ -1,9 +1,5 @@
 using System;
-using System.Collections.Generic;
 using System.IO;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using NewLife;
 using NewLife.Data;
 using NewLife.IoT.Protocols;
@@ -20,7 +16,8 @@ public void Test1()
         var dt = str.ToHex();
 
         var msg = new ModbusMessage();
-        msg.Read(dt);
+        var rs = msg.Read(dt);
+        Assert.Equal(dt.Length, rs);
         Assert.NotNull(msg);
 
         Assert.Equal(1, msg.Host);
@@ -42,7 +39,8 @@ public void Test2()
         var dt = str.ToHex();
 
         var msg = new ModbusMessage { Reply = true };
-        msg.Read(dt);
+        var rs = msg.Read(dt);
+        Assert.Equal(dt.Length, rs);
         Assert.NotNull(msg);
 
         Assert.Equal(1, msg.Host);
@@ -76,5 +74,6 @@ public void Set()
         msg.SetRequest(0x0002, 0xABCD);
 
         Assert.Equal("00-02-AB-CD", msg.Payload.ToHex(256, "-"));
+        Assert.Equal("WriteRegister (0x0002, ABCD)", msg.ToString());
     }
 }
\ No newline at end of file
diff --git a/XUnitTest/XUnitTest.csproj b/XUnitTest/XUnitTest.csproj
index 05a5ff9..f629093 100644
--- a/XUnitTest/XUnitTest.csproj
+++ b/XUnitTest/XUnitTest.csproj
@@ -14,7 +14,7 @@
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="9.0.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="Moq" Version="4.20.72" />
-    <PackageReference Include="NewLife.Core" Version="11.1.2024.1206" />
+    <PackageReference Include="NewLife.Core" Version="11.1.2024.1212-beta1042" />
     <PackageReference Include="xunit" Version="2.9.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
       <PrivateAssets>all</PrivateAssets>