XUI, Calling asmx web method with object parameter

Question

I have web service asmx has method GetDataBySystemUser(SystsemUser systemUser) takes object parameter. I can use Ajax to call this method passing object as JSON and working fine, but how to do that using xui and xhr like below code?

var url = "WebServiceTest.asmx/GetDataBySystemUser";

var SystemUser = new Object();
        SystemUser.Name = "Web";
        SystemUser.Status = "AWeb";

var FormData = JSON.stringify({ systemUser: SystemUser });

 x$('#bodyMain').xhr(url, {
            method: 'post',
            data: FormData,
            callback: function () {
                alert(this.responseText.d);
            }
        });