A 16-device register for station bus, process bus, switch management and SCADA DMZ is checked before it is issued. Seven errors and three warnings are found in seconds — each with its line number.
| Station bus, VLAN 1 | 10.13.0.0/25, gateway 10.13.0.1 — gateway, HMI, GPS clock, protection IEDs, bay controllers |
| Process bus, VLAN 20 | 10.13.0.128/26 — two merging units |
| Switch management, VLAN 99 | 10.13.0.192/27, gateway 10.13.0.193 — two switches, engineering PC |
| SCADA DMZ, VLAN 30 | 10.13.1.0/28, gateway 10.13.1.1 — gateway's second port |
| Input | Table copied from Excel (the built-in sample register) |
P132_Q01 and P87T_T1 are both 10.13.0.14 — the transformer protection line was copied from the feeder line and the address not changed.
BCU_J01 uses 255.255.255.0 while the rest of VLAN 1 uses /25. Its subnet 10.13.0.0/24 overlaps every other 10.13.0.x subnet in the register.
BCU_J02 has gateway 10.13.1.1, which is in the DMZ subnet, not in 10.13.0.0/25. The device can never reach it.
MU_Q01 and MU_T1 share 00-21-C1-11-00-0A. A real MAC is unique per device, so this is a copying error in the register — but if it were real, the switch would flip the address between two ports.
ENG-PC uses /26 while the switches use /27. Its subnet 10.13.0.192/26 overlaps 10.13.0.192/27.
LAPTOP is entered with 169.254.10.5 — copied from a laptop that was set to DHCP and had no DHCP server.
| Check | Requirement | Actual | Status |
|---|---|---|---|
| Duplicate IP / MAC | None | 1 IP, 1 MAC | ✗ FAIL |
| Unusable addresses | None | Broadcast 10.13.0.127, link-local 169.254.10.5 | ✗ FAIL |
| Gateways inside own subnet | All | BCU_J02 outside | ✗ FAIL |
| One mask per VLAN, no overlaps | Yes | 2 overlaps, 2 mask mixes | ✗ FAIL |
| Totals | 0 errors | 7 errors, 3 warnings, 2 notes | ✗ FAIL |
Key insight: Most register errors are copied lines. Duplicate checks on IP, MAC and name catch them before they reach site.
Every input in this example is editable in the live calculator — no signup needed.
Open IP Address Register Consistency Checker calculator →VLAN 1 and VLAN 99 each carry more than one subnet because of the wrong masks. They disappear once the masks are corrected.
Yes — write addresses as 10.13.0.14/25 and leave out the mask column.