User's Manual

Configuration Using the Wizards of Web Based Management
Operating Instructions SCALANCE W 788-1pro / SCALANCE W 788-2pro
40 C79000-G8976-C184-01
Subnet Mask Input Box
The subnet mask specifies the range of addresses within which communication
can take place.
The four numbers of an IP address separated by periods are interpreted as a bit
pattern. If a one is set at a bit position within the subnet mask, this means that only
devices with an IP address the matches the IP address of the SCALANCE W 788
at this bit position can communicate with the SCALANCE W 788.
Example
Let us assume that the IP address of the SCALANCE W 788 is set to
192.168.147.189 and the subnet mask is set to 255.255.255.0. The bit pattern for
255 is 1111 1111. This means that the bit pattern of the first number of the IP ad-
dress of a communication partner must match the bit pattern of the SCALANCE W
788 exactly at this point. The same applies to the second and third parts of the IP
address. The IP address of a communication partner must therefore start with
192.168.147. The bit pattern for 0 is 0000 0000. This means that the bit pattern of
the last part of the IP address of the partner device does not need to match the ad-
dress of the SCALANCE W 788 at any point; in other words, it can be any number.