Пример:

{
	DeviceType:  "TCP",
	Parameters: [{
        Type: "textfield",
	    Name: "Host",
        DefaultValue: "255.255.255.255",
        Validation: function(value) { // checking if value is empty 
         if (value == "") {
            return "Host is empty";
         } else
            return 0;
      }
	}]
}