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Networking·7 min read·

EtherNet/IP and PROFINET: same cable, different worlds

Both run on Ethernet and neither talks to the other, which is a fact of purchasing more than of engineering.

Short answer

Both are industrial Ethernet protocols and they are not interoperable. EtherNet/IP is the Rockwell-aligned standard, encapsulating CIP over standard TCP and UDP so it runs on ordinary switches. PROFINET is the Siemens-aligned standard, with real-time classes that bypass the normal stack for deterministic traffic. The choice is almost always dictated by the controller.

Which protocol sits whereENTERPRISEOPC UAMQTTCONTROLEtherNet/IPPROFINETModbus TCPDEVICEIO-LinkPROFIBUS DPModbus RTUEthernet carries most of it now, which is why the layers blur.

Both are industrial Ethernet. Both use the same cable and the same switches. Neither can talk to the other, and that is the practically important fact.

EtherNet/IP

CIP, the Common Industrial Protocol, carried over standard TCP and UDP. Because it sits on top of ordinary Ethernet, it works with commodity switches and standard network tooling.

Dominant wherever Rockwell is dominant, which is largely North America.

PROFINET

The Siemens-aligned standard, with tiers. The basic tier is ordinary Ethernet. The real-time tiers bypass parts of the normal stack, and the isochronous tier reserves time slots for deterministic motion.

Dominant wherever Siemens is dominant, which is largely Europe.

What actually decides it

The controller. You do not usually choose a protocol; you choose a PLC and inherit one.

Where it matters is in a mixed plant, because a device bought for one line may be useless on the next. Check the protocol before the specification sheet convinces you the device is the same one.

Crossing between them

Gateways exist and work. They also add a device to maintain, a mapping to document, and a place for latency to appear, so they are worth avoiding where a native device is available.

Common questions

Can EtherNet/IP and PROFINET run on the same network?
Physically yes, logically no. They can share cabling and switches because both use standard Ethernet framing, but devices on one protocol cannot talk to devices on the other. Crossing between them requires a gateway that maps data explicitly.
Which is faster, EtherNet/IP or PROFINET?
For ordinary I/O both are comfortably fast enough and the difference does not matter. PROFINET's IRT class achieves lower jitter for motion control by reserving time slots, which matters for coordinated axes and almost nowhere else.

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