diff --git a/Modbus.Net/Modbus.Net/Controller/BaseController.cs b/Modbus.Net/Modbus.Net/Controller/BaseController.cs
index 1fc7a19..ee22c23 100644
--- a/Modbus.Net/Modbus.Net/Controller/BaseController.cs
+++ b/Modbus.Net/Modbus.Net/Controller/BaseController.cs
@@ -92,15 +92,16 @@ namespace Modbus.Net
         /// <param name="def">需要添加的信息信息</param>
         protected virtual bool AddMessageToList(MessageWaitingDef def)
         {
+            var ans = false;
             lock (WaitingMessages)
             {
                 if (WaitingMessages.FirstOrDefault(p => p.Key == def.Key) == null || def.Key == null)
                 {
                     WaitingMessages.Add(def);
-                    return true;
+                    ans = true;
                 }
-                return false;
             }
+            return ans;
         }
 
         /// <summary>
@@ -116,10 +117,18 @@ namespace Modbus.Net
             var ans = new List<(byte[], bool)>();
             byte[] receiveMessageCopy = new byte[receiveMessage.Length];
             Array.Copy(receiveMessage, receiveMessageCopy, receiveMessage.Length);
-            var length = LengthCalc?.Invoke(receiveMessageCopy);
+            int? length = -1;
+            try
+            {
+                length = LengthCalc?.Invoke(receiveMessageCopy);
+            }
+            catch
+            {
+                //ignore
+            }
             List<byte[]> duplicatedMessages;
             if (length == null || length == -1) return ans;
-            if (length == 0) return null;
+            else if (length == 0) return null;
             else
             {
                 duplicatedMessages = new List<byte[]>();
diff --git a/Modbus.Net/Modbus.Net/Controller/DuplicateWithCount.cs b/Modbus.Net/Modbus.Net/Controller/DuplicateWithCount.cs
index f41f9ac..76108be 100644
--- a/Modbus.Net/Modbus.Net/Controller/DuplicateWithCount.cs
+++ b/Modbus.Net/Modbus.Net/Controller/DuplicateWithCount.cs
@@ -20,9 +20,10 @@ namespace Modbus.Net
             var ans = 0;
             foreach (var position in packageCountPositions)
             {
-                if (position >= receiveMessage.Length) return -1;
+                if (position > receiveMessage.Length - 1) return -1;
                 ans = ans * 256 + receiveMessage[position];
             }
+            if (ans + otherCount > receiveMessage.Length) return -1;
             return ans + otherCount;
         }
 
diff --git a/Modbus.Net/Modbus.Net/Controller/FifoController.cs b/Modbus.Net/Modbus.Net/Controller/FifoController.cs
index 28b3bdd..3baf686 100644
--- a/Modbus.Net/Modbus.Net/Controller/FifoController.cs
+++ b/Modbus.Net/Modbus.Net/Controller/FifoController.cs
@@ -76,9 +76,9 @@ namespace Modbus.Net
                                 _taskCycleSema?.Close();
                                 sendSuccess = true;
                             }
-                            else if (WaitingMessages.Count > WaitingMessages.IndexOf(_currentSendingPos) + 1)
+                            else if (WaitingMessages.IndexOf(_currentSendingPos) == -1)
                             {
-                                _currentSendingPos = WaitingMessages[WaitingMessages.IndexOf(_currentSendingPos) + 1];
+                                _currentSendingPos = WaitingMessages.First();
                                 _currentSendingPos.SendMutex.Set();
                                 sendSuccess = true;
                             }
diff --git a/Modbus.Net/Modbus.Net/Controller/MatchController.cs b/Modbus.Net/Modbus.Net/Controller/MatchController.cs
index 0ecc4e3..65153af 100644
--- a/Modbus.Net/Modbus.Net/Controller/MatchController.cs
+++ b/Modbus.Net/Modbus.Net/Controller/MatchController.cs
@@ -39,7 +39,7 @@ namespace Modbus.Net
                 int tmpCount = 0, tmpCount2 = 0;
                 foreach (var matchPos in matchPoses)
                 {
-                    if (matchPos.Item1 >= message.Length || matchPos.Item2 >= message.Length) return null;
+                    if (matchPos.Item1 > message.Length - 1 || matchPos.Item2 > message.Length - 1) return null;
                     tmpCount = tmpCount * 256 + message[matchPos.Item1];
                     tmpCount2 = tmpCount2 * 256 + message[matchPos.Item2];
                 }
diff --git a/Samples/MachineJob/Worker.cs b/Samples/MachineJob/Worker.cs
index f4cc07f..e97f132 100644
--- a/Samples/MachineJob/Worker.cs
+++ b/Samples/MachineJob/Worker.cs
@@ -94,6 +94,7 @@ namespace MachineJob.Service
                     _logger.LogInformation(dataReturnDef.MachineId + " " + value.Key + " " + value.Value.DeviceValue);
                 }
 
+                /*
                 try
                 {
                     using (var context = new DatabaseWriteContext())
@@ -119,7 +120,7 @@ namespace MachineJob.Service
                 {
                     //ignore
                 }
-
+                */
                 Random r = new Random();
                 foreach (var value in values)
                 {