Does your PLC program uses any of the following commands:
SAVE_EEP
LOAD_EEP
PRINT #1
OUTCOMM 1
NETCMD$(1,xx,xx)
READMODBUS (1,xx,xx) or READMODBUS (11,xx,xx)
WRITEMODBUS 1,xx,xx,xx or WRITEMODBUS 11,xx,xx,xx
READMB2 1,xx,xx,xx or READMB2 11,xx,xx,xx
WRITEMB2 1,xx,xx,xx,xx or WRITEMB2 11,xx,xx,xx,xx
These commands could potentially affect the serial communication with the XServer and resulted in loss communication. ExcelLink was designed to suspend the comm for 1 minute to give the network time to recover.
If you require continuous logging of data and cannot tolerate occasional loss of communication, you may want to consider using the File Service command provided by TLServer (or via the <RemoteFS> tag using XServer) and open data file on a PC, then write the data to be logged to the PC periodically.