Fieldbus Communication • 131ETHERNETWAGO-I/O-SYSTEM 750PROFINET IO4.1.3.4.4 DNS (Domain Name Systems)The DNS client enables conversion of logical Internet names such aswww.wago.com into the appropriate decimal IP address represented withseparator stops, via a DNS server. Reverse conversion is also possible.The addresses of the DNS server are configured via DHCP or web-basedmanagement. Up to 2 DNS servers can be specified. The host identificationcan be achieved with two functions, an internal host table is not supported.4.1.3.4.5 SNTP-Client (Simple Network Time Protocol)The SNTP client is used for synchronization of the time of day between a timeserver (NTP and SNTP server Version 3 and 4 are supported) and the clockmodule integrated in the (programmable) fieldbus coupler or controller. Theprotocol is executed via a UDP port. Only unicast addressing is supported.Configuration of the SNTP clientThe configuration of the SNTP client is performed via the web-basedmanagement system under the “Clock” link. The following parameters mustbe set:Parameter MeaningAddress of theTime serverThe address assignment can be made either over a IP address or a hostname.Time zone The time zone relative to GMT (Greenwich Mean time). A range of -12 to +12 hours is acceptable.Update Time The update time indicates the interval in seconds, in which thesynchronization with the time server is to take place.Enable TimeClient It indicates whether the SNTP Client is to be activated or deactivated.4.1.3.4.6 FTP-Server (File Transfer Protocol)The file transfer protocol (FTP) enables files to be exchanged betweendifferent network stations regardless of operating system.In the case of the ETHERNET coupler/controller, FTP is used to store andread the HTML pages created by the user, the IEC61131 program and theIEC61131 source code in the (programmable) fieldbus coupler or controller.A total memory of 1.5 MB is available for the file system. The file system ismapped to RAM disk. To permanently store the data of the RAM disk, theinformation is additionally copied into the flash memory. The data is stored inthe flash after the file has been closed. Due to the storage process, accesstimes during write cycles are long.
