Viper User
Manual (001-5008-000 Rev6)
Page
25
CHOOSING AN IP ADDRESSING SCHEME
All Ethernet capable devices, or hosts, have at least one IP address and subnet mask
assigned to it. The IP address identifies that specific device and the subnet mask tells the
device which other IP addresses it can directly communicate with.
The Viper ships from the factory with a default Ethernet IP address of 192.168.205.1 and a
subnet mask of 255.255.255.0. (This is sometimes written in shorthand notation as:
192.168.205.1/24 since the subnet mask 255.255.255.0 contains 24 ones then 8 zeros
when it is converted to binary.)
The default subnet of the Viper consists of addresses from 192.168.205.0 to
192.168.205.255. The first and last IP address of each subnet is reserved, no matter what
the subnet size is. The first IP address in the subnet is the Network ID. The last IP address
in the subnet is the Broadcast Address. In the Viper’s example, IP addresses 192.168.205.0
and 192.168.205.255 are reserved, and any address(es) from 192.168.205.1 to
192.168.205.254 are valid and may be assigned to a host.
When any host needs to communicate with another device that is not within the same local
area network it will first send the data packet to the gateway or router. The gateway or
router will forward the packet to the desired location. Often times a packet will pass
through several gateways or routers to get to its final destination.
1.1.23
Bridge Mode
In Bridge mode each Viper has only one IP address. Each Viper in the network must be on
the same network and have the same subnet mask. It is recommended that each Viper be
assigned a unique IP address.
Bridge Mode Example 1:
Ethernet Subnet Mask for all units: 255.255.255.0
Network
ID:
192.168.205.0
Viper
#1:
192.168.205.1
/
24
Viper
#2:
192.168.205.2
/
24
Viper
#3:
192.168.205.3
/
24
PLC/RTU #1:
192.168.205.4 / 24
PLC/RTU #2:
192.168.205.5 / 24
Computer #1:
192.168.205.6 / 24
…
PLC/RTU #100:
192.168.205.253 / 24
Viper #100:
192.168.205.254 / 24
Broadcast Address: 192.168.205.255
All units are on the 192.168.205.0 network and all units have the same subnet mask.
Because of this, all units can communicate directly with each other. There are 254 valid
IP addresses that may be assigned to hosts on the network.