1. Resolved the hourly connection termination problem in non-TLS firmware communication.

2. Enhanced socket-level data packet reception throughput.

DriverTest/Program.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.IO;
 using System.Security.Cryptography;
 using System.Text;
+using System.Threading.Tasks;
 using S7CommPlusDriver;
 
 using S7CommPlusDriver.ClientApi;
@@ -38,6 +39,7 @@ namespace DriverTest
             stopwatch1.Start();
             res = conn.Connect(HostIp, Password);
             stopwatch1.Stop();
+            byte[] var1_crc_bytes = { 0x88, 0xdd, 0xa4, 0x83, 0x34 };
             Console.WriteLine($"PLCType: {conn.PLCInformation.PLCType} | MLFB: {conn.PLCInformation.MLFB} | Firmware: {conn.PLCInformation.Firmware}");
             Console.WriteLine($"连接耗时{stopwatch1.ElapsedMilliseconds}ms.");
             if (res == 0)
@@ -59,17 +61,13 @@ namespace DriverTest
                 Console.WriteLine("Main - Lese Werte aller Variablen aus");
 
                 List<PlcTag> taglist = new List<PlcTag>();
-                PlcTags tags = new PlcTags();
 
                 foreach (var v in vars_)
                 {
                     ItemAddress itemAddress = new ItemAddress(v.AccessSequence);
+                    //S7p.DecodeUInt32Vlq(new MemoryStream(var1_crc_bytes), out itemAddress.SymbolCrc);
                     taglist.Add(PlcTags.TagFactory(v.Name, itemAddress, v.Softdatatype));
                 }
-                foreach (var t in taglist)
-                {
-                    tags.AddTag(t);
-                }
                 if (res == 0)
                 {
                     Console.WriteLine("====================== VARIABLENHAUSHALT ======================");
@@ -85,13 +83,21 @@ namespace DriverTest
                     }
                 }
                 #endregion
-                Console.WriteLine("按任意键开始读");
+                Console.WriteLine("按任意键开始读或订阅");
                 Console.ReadKey();
+                res = conn.SubscriptionCreate(taglist, 100);
+                if (res == 0)
+                {
+                    Task.Run(() =>
+                    {
+                        conn.TestWaitForVariableChangeNotifications(50000000000);
+                    });
+                }
                 while (res == 0)
                 {
                     System.Diagnostics.Stopwatch stopwatch2 = new System.Diagnostics.Stopwatch();
                     stopwatch2.Start();
-                    res = tags.ReadTags(conn);
+                    res = PlcTags.ReadTags(conn, taglist);
                     stopwatch2.Stop();
                     long ms = stopwatch2.ElapsedMilliseconds;
                     if (res == 0)
@@ -99,7 +105,7 @@ namespace DriverTest
                         string header = $"读取{vars_.Count}个变量耗时{ms}毫秒";
                         Console.WriteLine(header);
                     }
-                    System.Threading.Thread.Sleep(10);
+                    //System.Threading.Thread.Sleep(50);
                 }
 #endif
 
@@ -196,4 +202,80 @@ namespace DriverTest
             Console.ReadKey();
         }
     }
+    public static class S7SymbolCrc32
+    {
+        private const uint Polynomial = 0xFA567993; // 多项式(x³² + x³¹ + x³⁰ + x²⁹ + x²⁸ + x²⁶ + x²³ + x²¹ + x¹⁹ + x¹⁸ + x¹⁵ + x¹⁴ + x¹³ + x¹² + x⁹ + x⁸ + x⁴ + x + 1)
+        private const uint InitialValue = 0xFFFFFFFF;
+        private static readonly uint[] Table;
+
+        static S7SymbolCrc32()
+        {
+            // 预计算CRC表
+            Table = new uint[256];
+            for (uint i = 0; i < 256; i++)
+            {
+                uint crc = i << 24;
+                for (int j = 0; j < 8; j++)
+                {
+                    if ((crc & 0x80000000) != 0)
+                    {
+                        crc = (crc << 1) ^ Polynomial;
+                    }
+                    else
+                    {
+                        crc <<= 1;
+                    }
+                }
+                Table[i] = crc;
+            }
+        }
+
+        /// <summary>
+        /// 计算S7CommPlus符号名的CRC32校验和
+        /// </summary>
+        /// <param name="symbolName">符号名（如"DB1.TempBottom"）</param>
+        /// <param name="dataType">数据类型字节</param>
+        /// <returns>CRC32校验和</returns>
+        public static uint CalculateSymbolCrc(string symbolName)
+        {
+            // 1. 替换分隔符 '.' → 0x09
+            string processedName = symbolName.Replace('.', '\t');
+
+            // 2. 转换为字节数组
+            byte[] nameBytes = Encoding.ASCII.GetBytes(processedName);
+
+            // 3. 添加数据类型字节
+            byte[] data = new byte[nameBytes.Length];
+            Array.Copy(nameBytes, 0, data, 0, nameBytes.Length);
+
+            // 4. 计算CRC32
+            uint crc = InitialValue;
+            foreach (byte b in data)
+            {
+                crc = (crc << 8) ^ Table[((crc >> 24) & 0xFF) ^ b];
+            }
+
+            // 5. 根据作者提示，可能需要再次计算（需要验证）
+            //crc = CalculateSecondPass(crc);
+
+            return crc;
+        }
+
+        // 如果需要二次计算的方法
+        public static uint CalculateSecondPass(uint firstResult)
+        {
+            byte[] crcBytes = BitConverter.GetBytes(firstResult);
+            if (BitConverter.IsLittleEndian)
+            {
+                Array.Reverse(crcBytes); // 确保大端序
+            }
+
+            uint crc = InitialValue;
+            foreach (byte b in crcBytes)
+            {
+                crc = (crc << 8) ^ Table[((crc >> 24) & 0xFF) ^ b];
+            }
+            return crc;
+        }
+    }
 }