后台调用JS函数问题

Question

    <script language="javascript" type="text/javascript">
       
       function OpenCom(ComPort,Baud)
       {
        var res = document.getElementById("cms");
        if(res.ConnectPort(ComPort,Baud))
        {
            document.getElementById("tuser").value="true";
            //alert("打开成功！");
        }
        else
        {
            document.getElementById("tuser").value="false";
            //alert("打开失败！");
         }
         document.getElementById("Button4").click();
        //res.DisConnectPort();
       }
       
       function WriteData(SendData,DataLenth)
       {
        var res = document.getElementById("cms");
        if(res.WriteComData(SendData,DataLenth)>0)
        {
            //alert(" 发送成功！");
        }
        else
            alert("发送失败！");
       }
       function DisConnectPort()
       {
        var res = document.getElementById("cms");
        res.DisConnectPort();
        }    </script>上面是JS函数 下面的前台调用也是没问题的
<input value="打开串口" type="button" onclick="OpenCom(2,57600)"; />
      <input value="发送数据" type="button" onclick="WriteData('1234567890',10)"; />
      <input value="关闭串口" type="button" onclick="DisConnectPort()"; />现在需要后台调用JS函数//打开串口
protected void Button1_Click(object sender, EventArgs e) 
        {   int ComReport = Int32.Parse(DropDownList1.Text.Trim());
            int Btl = Int32.Parse(DropDownList2.Text.Trim());
            this.ClientScript.RegisterStartupScript(GetType(), "", "OpenCom('" + ComReport + "','" + Btl + "')", true);
        }
//发送数据
        protected void Button2_Click(object sender, EventArgs e)
        {
            byte[] b = Encoding.Default.GetBytes(Convert.ToString(TextBox1.Text.Trim()));
            int Len_Values = b.Length;
            this.ClientScript.RegisterStartupScript(GetType(), "", "WriteData('1234',4)", true);
        }打开串口是成功的
发送串口数据失败

Answer 1

什么意思？
后台不是可以调用前台JS吗？