Every automation engineer has spent an hour hunting a device that was “definitely at .12”. Machine network addressing deserves five minutes of design before the first download.
A scheme that scales
For a standalone machine we allocate a /24 per machine and keep roles in fixed ranges: PLC at .1, HMIs from .10, drives from .20, distributed I/O from .40, vision and third-party gear from .60, service laptop expected at .200. The pattern repeats across every machine we ship, which means a service engineer knows the layout before opening the project.
Two rules matter more than the specific numbers:
- The pattern is identical on every machine you build. Familiarity is the actual feature.
- Document the plant-integration plan. The machine’s /24 will one day meet a plant network; NAT routers or a reserved plant range prevent the classic duplicate-IP crisis.
Profinet names are not decoration
Profinet devices are addressed by device name first; the IP follows. Name devices functionally — infeed-drive, saw-axis, exit-io — not by catalog number. When a drive is replaced at 3 a.m., topology-based name assignment can configure the spare automatically, but only if your names and topology are deliberate.
FAQ
DHCP on machine networks? No. Deterministic addresses for deterministic machines. DHCP belongs on the office side of the firewall.
What about the second Ethernet port on S7-1500 CPUs? Use it. Keeping the machine network (X1) separated from the plant/SCADA network (X2) is the cheapest network segmentation you will ever buy.
Zone Otomasyon designs and commissions Profinet networks for machines and retrofits. Ask us before the addressing becomes archaeology.