dump element configuration json string for online modeling,
        in which control configuration should be overwritten simulation conf,
        e.g. in simuinfo: {'k1':10,'l':1}, ctrlinfo: {'k1':pv_name,...}
        the k1 value should be replaced by pv_name, and from which
        the value read into, take note the simuinfo and ctrlinfo
        would not be changed.

def _dumpOnlineConf(self, format):
        """ dump element configuration json string for online modeling,
        in which control configuration should be overwritten simulation conf,
        e.g. in simuinfo: {'k1':10,'l':1}, ctrlinfo: {'k1':pv_name,...}
        the k1 value should be replaced by pv_name, and from which
        the value read into, take note the simuinfo and ctrlinfo
        would not be changed.
        """
        oinfod = {k: v for k, v in self.simuinfo.items()}
        for k in (set(oinfod.keys()) & set(self.ctrlkeys)):
            oinfod[k] = self.ctrlinfo[k]
        return {self.name.upper(): {self.typename: oinfod}}