diff --git a/Example/Gateway/Script/View/ViewModbusGateway.cs b/Example/Gateway/Script/View/ViewModbusGateway.cs
index 8bab602..c6d5600 100644
--- a/Example/Gateway/Script/View/ViewModbusGateway.cs
+++ b/Example/Gateway/Script/View/ViewModbusGateway.cs
@@ -17,8 +17,9 @@ namespace EGFramework.Examples.Gateway{
 			ReadTest2();
 			ReadTest3();
 			ReadTest3();
-			ReadTest2();
-			ReadTest();
+			// ReadTest2();
+			// ReadTest();
+			WriteTest1();
 		}
 
 		// Called every frame. 'delta' is the elapsed time since the previous frame.
@@ -76,6 +77,19 @@ namespace EGFramework.Examples.Gateway{
 				GD.Print("Timeout!");
 			}
 		}
+
+		public async void WriteTest1(){
+			ModbusRTU_Response? result = await this.EGModbus().WriteOnceRTUAsync(ModbusRegisterType.HoldingRegister,"COM4",0x01,0x2000,0x50);
+			if(result != null){
+				if(!((ModbusRTU_Response)result).IsError){
+					GD.Print("Write[0]"+((ModbusRTU_Response)result).FunctionType);
+				}else{
+					GD.Print("Error:"+((ModbusRTU_Response)result).ErrorCode);
+				}
+			}else{
+				GD.Print("Timeout!");
+			}
+		}
 		
 	}
 }
diff --git a/addons/EGFramework/Module/ProtocolTools/EGModbus.cs b/addons/EGFramework/Module/ProtocolTools/EGModbus.cs
index abf7d98..c9c4fc7 100644
--- a/addons/EGFramework/Module/ProtocolTools/EGModbus.cs
+++ b/addons/EGFramework/Module/ProtocolTools/EGModbus.cs
@@ -35,15 +35,15 @@ namespace EGFramework{
             this.EGOnMessage<ModbusTCP_Response>();
         }
 
-        public bool IsReadingRTU { set; get; }
+        private bool IsRequestRTU { set; get; }
         public async Task<ModbusRTU_Response?> ReadRTUAsync(ModbusRegisterType registerType,string serialPort,byte deviceAddress,ushort start,ushort count){
-            if(IsReadingRTU){
+            if(IsRequestRTU){
                 SendPointerRTU++;
                 int messageId = SendPointerRTU;
                 WaitForSendRTU.Enqueue(messageId);
                 await Task.Run(async () =>
                 {
-                    while (IsReadingRTU || NextSendRTU != messageId)
+                    while (IsRequestRTU || NextSendRTU != messageId)
                     {
                         await Task.Delay(10);
                         //break;
@@ -53,7 +53,7 @@ namespace EGFramework{
                 //return null;
             }
             RTUCache.Clear();
-            IsReadingRTU = true;
+            IsRequestRTU = true;
             IRequest ReadRequest;
             ModbusRTU_Response? res = null;
             switch(registerType){
@@ -76,22 +76,73 @@ namespace EGFramework{
                 }else{
                     //Print Error Timeout
                     OnReadTimeOut.Invoke();
-                    this.EGSerialPort().ClearBuffer(serialPort);
                 }
             });
-            IsReadingRTU = false;
+            this.EGSerialPort().ClearReceivedCache(serialPort);
+            IsRequestRTU = false;
             if(this.WaitForSendRTU.Count>0){
                 NextSendRTU = this.WaitForSendRTU.Dequeue();
             }
             return res;
         }
 
-        public bool IsReadingTCP { set; get; }
+        public async Task<ModbusRTU_Response?> WriteOnceRTUAsync(ModbusRegisterType registerType,string serialPort,byte deviceAddress,ushort registerAddress,ushort value){
+            if(IsRequestRTU){
+                SendPointerRTU++;
+                int messageId = SendPointerRTU;
+                WaitForSendRTU.Enqueue(messageId);
+                await Task.Run(async () =>
+                {
+                    while (IsRequestRTU || NextSendRTU != messageId)
+                    {
+                        await Task.Delay(10);
+                        //break;
+                    }
+                });
+                GD.Print("-----Write"+messageId+" ----");
+                //return null;
+            }
+            RTUCache.Clear();
+            IsRequestRTU = true;
+            IRequest ReadRequest;
+            ModbusRTU_Response? res = null;
+            switch(registerType){
+                case ModbusRegisterType.HoldingRegister:
+                    ReadRequest = new ModbusRTU_WriteSingleHoldingRegister(deviceAddress,registerAddress,value);
+                    // this.AppendMessage("【发送-"+DataModbusItem.SerialPort+"】 "+ReadRequest.ToProtocolByteData().ToStringByHex());
+                    this.EGSendMessage(ReadRequest,serialPort,ProtocolType.SerialPort);
+                    // this.EGSerialPort().SetExpectReceivedDataLength(5+count*2);
+                    this.EGSerialPort().SetExpectReceivedDataLength(ReadRequest.ToProtocolByteData().Length);
+                    break;
+            }
+            await Task.Run(async ()=>{
+                int timeout = 0;
+                while(RTUCache.Count==0 && timeout < Delay){
+                    await Task.Delay(10);
+                    timeout+=10;
+                }
+                if(RTUCache.Count>0){
+                    res = RTUCache.Dequeue();
+                }else{
+                    //Print Error Timeout
+                    OnReadTimeOut.Invoke();
+                }
+            });
+            this.EGSerialPort().ClearReceivedCache(serialPort);
+            IsRequestRTU = false;
+            if(this.WaitForSendRTU.Count>0){
+                NextSendRTU = this.WaitForSendRTU.Dequeue();
+            }
+            return res;
+        }
+
+
+        private bool IsRequestTCP { set; get; }
         public async Task<ModbusTCP_Response?> ReadTCPAsync(ModbusRegisterType registerType,string ipPort,byte deviceAddress,ushort start,ushort count){
-            if(IsReadingTCP){
+            if(IsRequestTCP){
                 await Task.Run(async () =>
                 {
-                    while (IsReadingTCP)
+                    while (IsRequestTCP)
                     {
                         await Task.Delay(10);
                         //break;
@@ -100,7 +151,7 @@ namespace EGFramework{
                 //return null;
             }
             TCPCache.Clear();
-            IsReadingTCP = true;
+            IsRequestTCP = true;
             IRequest ReadRequest;
             ModbusTCP_Response? res = null;
             switch(registerType){
@@ -123,7 +174,7 @@ namespace EGFramework{
                     OnReadTimeOut.Invoke();
                 }
             });
-            IsReadingTCP = false;
+            IsRequestTCP = false;
             return res;
         }
 
diff --git a/addons/EGFramework/Module/ProtocolTools/EGSerialPort.cs b/addons/EGFramework/Module/ProtocolTools/EGSerialPort.cs
index 21db30a..0a9e8d1 100644
--- a/addons/EGFramework/Module/ProtocolTools/EGSerialPort.cs
+++ b/addons/EGFramework/Module/ProtocolTools/EGSerialPort.cs
@@ -23,7 +23,7 @@ namespace EGFramework{
 
         public Queue<ResponseMsg> ResponseMsgs { set; get; } = new Queue<ResponseMsg>();
 
-        public byte[] ReceivedCache { set; get; } = new byte[0];
+        public Dictionary<string,byte[]> ReceivedCache { set; get; } = new Dictionary<string,byte[]>();
 
         public void Init()
         {
@@ -77,6 +77,7 @@ namespace EGFramework{
                 if(!SerialPortDevices.ContainsKey(serialPort)){
                     SerialPort newPort = new SerialPort(serialPort, DefaultBaudRate, Parity.None, 8, StopBits.One);
                     SerialPortDevices.Add(serialPort,newPort);
+                    ReceivedCache.Add(serialPort,new byte[0]);
                     if (!SerialPortDevices[serialPort].IsOpen)
                     {
                         SerialPortDevices[serialPort].Open();
@@ -176,19 +177,19 @@ namespace EGFramework{
                 int bufferSize = serialPort.BytesToRead;
                 byte[] buffer = new byte[bufferSize];
                 serialPort.Read(buffer,0,serialPort.BytesToRead);
-                ReceivedCache = ReceivedCache.Concat(buffer).ToArray();
+                ReceivedCache[serialPort.PortName] = ReceivedCache[serialPort.PortName].Concat(buffer).ToArray();
             }
-            if(ReceivedCache.Length >= MinDataPackLength){
-                string str = StringEncoding.GetString(ReceivedCache);
-                Godot.GD.Print("[Receive]"+ReceivedCache.ToStringByHex());
-                ResponseMsgs.Enqueue(new ResponseMsg(str,ReceivedCache,serialPort.PortName,ProtocolType.SerialPort));
-                ReceivedCache = new byte[0];
+            if(ReceivedCache[serialPort.PortName].Length >= MinDataPackLength){
+                string str = StringEncoding.GetString(ReceivedCache[serialPort.PortName]);
+                Godot.GD.Print("[Receive]"+ReceivedCache[serialPort.PortName].ToStringByHex());
+                ResponseMsgs.Enqueue(new ResponseMsg(str,ReceivedCache[serialPort.PortName],serialPort.PortName,ProtocolType.SerialPort));
+                ReceivedCache[serialPort.PortName] = new byte[0];
                 MinDataPackLength = 0;
                 //this.EGOnReceivedData(new ResponseMsg(str,buffer,serialPort.PortName,ProtocolType.SerialPort));
             }else{
-                Godot.GD.Print("[Data Get]" + ReceivedCache.Length);
-                string str = StringEncoding.GetString(ReceivedCache);
-                ResponseMsgs.Enqueue(new ResponseMsg(str,ReceivedCache,serialPort.PortName,ProtocolType.SerialPort));
+                Godot.GD.Print("[Data Get]" + ReceivedCache[serialPort.PortName].Length);
+                string str = StringEncoding.GetString(ReceivedCache[serialPort.PortName]);
+                ResponseMsgs.Enqueue(new ResponseMsg(str,ReceivedCache[serialPort.PortName],serialPort.PortName,ProtocolType.SerialPort));
             }
         }
 
@@ -196,15 +197,8 @@ namespace EGFramework{
             this.MinDataPackLength = leastLength;
         }
 
-        public void ClearBuffer(string serialPort){
-            if(SerialPortDevices.ContainsKey(serialPort)){
-                if (SerialPortDevices[serialPort].IsOpen)
-                {
-                    SerialPortDevices[serialPort].DiscardInBuffer();
-                }
-            }else{
-                //Not found in SerialPortDevices,need add?
-            }
+        public void ClearReceivedCache(string serialPort){
+            ReceivedCache[serialPort] = new byte[0];
         }
 
         public IArchitecture GetArchitecture()