Nano-10 only has 1 RS485 port so if you use it via TLServer for programming and online monitoring, then it is used as a slave port and your PLC program cannot use it to talk to the MDS100-BW while online monitoring is going on. Otherwise the PLC program will disrupt the communication between the PC and the PLC.
Since Nano-10 has an Ethernet port, all you need to do is to program or monitor through the Ethernet port and then the PLC's RS485 port is then freed to be used to talk to MDS100.
You can either connect Nano-10 to a switch or the router (preferred method), or connect the PC's Ethernet port directly to the Nano-10's Ethernet port (less desirable but still possible). The method has been described in details in Chapter 2 of the Nano-10 User's Manual.
Once properly connected you can then use TRiLOGI to access the Nano-10's IP address directly (you don't need to run TLServer at all), I believe this will be the best way to use your Nano-10 PLC since both program transfer and online monitoring are MUCH FASTER via the Ethernet port than the RS485 port.