The XServer only support the T100MD+ native protocol and does not support the MODBUS protocol.
DAQFactory SCADA supports the MODBUS RTU for direct connection to the PLC via the MODBUS. But it does not support the communication with the PLC via native protocol through a XServer login sequence hence this cannot be used. DAQFactory would need a driver to talk to the PLC through the XServer but I don't think they have developed one yet.