Together with a device's IP address, a subnet mask determines which IP network the device belongs to and which other addresses it can directly reach within its own network. It logically divides the IP address into a network portion (network prefix) and a device portion. The network portion must be identical for all devices on the same network, while the device portion must be unique for each device.
The Role of the Subnet Mask in an IP Network
A device uses the subnet mask to determine whether a destination IP address is on the same subnet or whether communication must go through a router to another network. All devices on a shared IP network should therefore be configured with the same subnet mask so that they can correctly locate and communicate with one another. Incorrectly set subnet masks typically result in devices on the same physical network being unreachable or having limited communication capabilities.
Practical Applications in Measurement Technology
In industrial measurement technology and in networked measurement and data acquisition systems, a correctly configured subnet mask is essential for reliable access to measuring devices via Ethernet. For Delphin systems that are integrated via IP into existing corporate networks, control rooms, or remote access solutions, the IP address, subnet mask, and, if applicable, gateway address must be set to match the respective subnet. Only then can PC software, control rooms, or other network components reliably retrieve measurement data, perform configurations, and communicate with devices in distributed systems without disruption.