Siemens SIMATIC S7 System Manual page 216

Program instructions
7.3 Communication
Similarly, consider the octets of the subnet mask "255.255.255.0":
Octet decimal value
255
255
255
0
You would use the combined hexadecimal values of the octets to form the MASK input to the
SIP_ADDR instruction: 16#FFFFFF00. You could also use the decimal equivalent, but not a
string representation.
The following program status display shows two networks:
● Network 1: The GIP_ADDR reads the IP address of 192.168.2.150 with a subnet mask of
255.255.255.0.
● Network 2: The SIP_ADDR sets the IP address to 192.168.2.150 (16#C0A80296) and
sets the subnet mask to 255.255.255.0 (16#FFFFFF00).
Note that the default gateway is 0.
216
Hexadecimal value
FF
FF
FF
00
System Manual, V2.3, 07/2017, A5E03822230-AF
S7-200 SMART