I assume the master PLC connects to the slave PLCs via RS485. So is TLServer connected to the RS232 port of the master PLC? Is it a one-to-one connection between the TLServer and the master PLC? If so then you can use the "IR*" command to test. If not, what is the ID of the master PLC? E.g. if master PLC ID is 01, You can then enter "@01IR00*" to see if it respond.
Or is the master PLC connected to the XServer in order to connect to the computer network? If so, then how does the TLServer connect to the master PLC? There will not be any more free serial port on the master PLC for TLServer to connect to in this case. If you connect the TLServer to the RS485 port of the master PLC then you will have a problem because the master PLC is sending out commands via its RS485 port to the slave PLCs and the port is therefore not available as a slave port to the TLServer.