Siemens S7-1200 System Manual page 156

Device configuration
5.7 Configuring the CPU for communication
If your programming device is using an Ethernet-to-USB adapter card connected to an
isolated network, the IP Address Network ID and subnet mask of your CPU and the
programming device's Ethernet-to-USB adapter card must be exactly the same. The Network
ID is the first part of the IP address (first three octets) (for example, 211.154.184.16) that
determines what IP network you are on. The subnet mask normally has a value of
255.255.255.0. The subnet mask, when combined with the device IP address in a
mathematical AND operation, defines the boundaries of an IP subnet.
Note
An Ethernet-to-USB adapter card is useful when you do not want your programming device
on your company LAN. During initial testing or commissioning tests, this arrangement is
particularly useful.
Table 5- 8 Assigning Ethernet addresses
Programming Device Network Type
Adapter Card
On-board adapter Connected to
card your plant LAN
(and possibly
the world-wide
web)
Ethernet-to-USB Connected to an
adapter card isolated network
The Network ID is the first part of the IP address (first three octets) (for example, 211.154.184.16) that determines what
1
IP network you are on.)
The subnet mask, when combined with the device IP address in a mathematical AND operation, defines the boundaries
2
of an IP subnet.
156
Internet Protocol (IP) Address
Network ID of your CPU and the
programming device's on-board
adapter card must be exactly the
same.
1
Network ID of your CPU and the
programming device's Ethernet-to-
USB adapter card must be exactly
the same.
1
Subnet Mask
The subnet mask of your CPU and the
on-board adapter card must be exactly
the same.
The subnet mask normally has a value of
255.255.255.0; however, since your
computer is on a plant LAN, the subnet
mask may have various values (for
example, 255.255.254.0) in order to set
up unique subnets.
2
The subnet mask of your CPU and the
Ethernet-to-USB adapter card must be
exactly the same.
The subnet mask normally has a value of
255.255.255.0.
2
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG