If the PLC name and socket port number entered in the Melsec property tab are not configured in your host file, the following message will appear in the log file:
Gethostname for <hostname> failed errno <number>
To resolve this problem, configure the host name into your computer system as described in step 5 of the Melsec PLC Communications Configuration Checklist. Remember that the names or aliases must match exactly.
Mitsubishi TCP/IP troubleshooting.