c# webform调用OCX控件问题 操作本地串口 打开串口没反映

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>操作本地串口</title>
    <script language="javascript" for="btnTest" event="onclick">
    <!--
       var ocxobject  = document.getElementById('cms');
    // -->
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <object id="cms" name="cms" classid="CLSID:0837F460-AD78-44C3-942F-958C11EE00D5" codebase="/CityBusReader.ocx"></object>
        <input id="btnTest" size="10" type="button"   value="调用"  onchange="javascript:ocxobject.ConnectPort(1,57600)" />
    <div>
    
    </div>
    </form>
</body>
</html>