IP Subnet Calculator for Control Networks
Enter an IP address and prefix length to get the network address, broadcast, usable host range and subnet mask, and check whether two devices are on the same subnet.
How It Works
Broadcast = network OR (NOT mask)
Usable hosts = 2^(32 − n) − 2
n is the prefix length: /24 means a mask of 255.255.255.0. The first address is the network and the last the broadcast; the rest are for devices.
Worked example
192.168.10.25/24: network 192.168.10.0, broadcast 192.168.10.255, hosts 192.168.10.1 to 192.168.10.254 (254 hosts).
Frequently Asked Questions
What does /24 mean?
The first 24 bits are the network part, giving mask 255.255.255.0 and 254 usable hosts.
Why can my laptop not reach the PLC?
Often a different subnet or mask; set the laptop to an address in the PLC subnet.
Should control networks be separated?
Yes, segment control networks from office networks with firewalls, as recommended by IEC 62443.
Learn more on the blog
Subnet and VLAN differences
A practical, field focused guide on instrumentationblog.in that explains the theory behind this tool and how engineers apply it on real plants.
Read Full Article