PROFINET device name (NameOfStation) and DCP
How a PROFINET device gets its name and IP address, the exact naming rules and the mistakes that stop a device from starting.
Why names, not addresses
A new PROFINET IO device has a MAC address but no device name. The engineer assigns a name once (online with the engineering tool, from a memory card or automatically via topology). From then on the controller addresses the device by name: at startup it sends a DCP Identify request for the configured name, the device answers, and the controller sets the configured IP address with DCP Set. Replacing a defective device therefore only requires giving the new one the same name.
Naming rules
The NameOfStation is defined by the PROFINET standard (IEC 61158-6-10); device documentation summarizes it as:
| Rule | Detail |
|---|---|
| Total length | 1 … 240 characters |
| Labels | one or more labels separated by ., each 1 … 63 characters |
| Characters | a-z, 0-9, - — lower case only |
| Hyphen | a label must not start or end with - |
| Reserved forms | the name must not have the form n.n.n.n (n = 0…999) |
| Reserved forms | the first label must not be port-xyz or port-xyz-abcde (digits) |
Controllers may limit the length further (for example 127 characters in some PLC families). Names with capitals, spaces, _ or national characters are converted by engineering tools (STEP 7 turns them into an encoded form like xb1…), which is hard to read on site — use DNS-style names from the start: pump-101.line2.plant.
Check a name with the device name validator.
IP address assignment
- Usually set by the IO controller from the project — the device only needs the correct name.
- Alternatively set "on the device" (DCP from a tool, DHCP) when the project allows it.
- The address must be unique; a duplicate address or name is reported in diagnostics and prevents the device from starting.
Typical startup errors
| Symptom | Cause |
|---|---|
| Device not found, BF LED flashing | No name or a different name assigned |
| Two devices answer to one name | Name assigned twice (after copying a machine) |
| Device found but no data | Wrong GSDML version or module configuration mismatch |
| Works until replacement | Replacement device delivered with a name from the previous installation; reset to factory settings and reassign |
Connections
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Sources
- Anybus CompactCom 40 PROFINET — Station Name (Network Configuration Object, instance 20) — HMS Networks
- PROFINET with STEP 7 — Function Manual 11/2022 — Siemens AG
- PROFINET System Description, System Manual 03/2012 — Siemens AG
- PROFINET — technology overview — PROFIBUS & PROFINET International (PI)
Updated 2026-10-02