Note that WXI command is supported on firmware revision of r47 or later.
Please use the multi-point format, i.e. if your PLC has address=01 then try:
@01WXI000101FF00*
and it should work. You can also replace the last two zeros "00" with the FCS computed by pressing the "FCS" button.
The TLServer intentionally forbid point-to-point protocol to prevent careless error of writing to multiple PLCs that are linked via RS485. The only point-to-point command that is recognized by TLServer is "IR*".