How to read a Siemens order number

A Siemens article number — the Bestellnummer or MLFB — is not a serial number and not a random code. It is a structured description of the article: read it and you can tell whether two parts are candidates for the same position. Confirm the match on Siemens’ own product page, because Siemens’ explanations of its number schemes do not cover every combination.

How do I read a Siemens order number?

Read it block by block from the left. The first four characters name the product group (6ES7 is SIMATIC S7), the next digits the family and type, the two digits before the last hyphen the functional version, and the final block the variant or packaging. Spaces and hyphens carry no meaning.

Most Siemens automation numbers follow the same layout:

6ES7 315-2EH14-0AB0
│    │   │    │  └── variant / packaging
│    │   │    └───── functional version
│    │   └────────── type within the family
│    └────────────── family / series
└─────────────────── product group

The first block identifies the product group and is the fastest way to know what you are looking at:

Reading an S7 CPU number

Take 6ES7 315-2EH14-0AB0.

• 6ES7 — SIMATIC S7.
• 315 — CPU 315, an S7-300 CPU. The S7-300 family is now in its spare-parts phase; the S7-300 migration guide has the dates.
• -2 — the interface variant: 2 here denotes the two-interface version (MPI/DP plus PROFINET on the EH types).
• EH — the specific execution. 2EH is the CPU 315-2 PN/DP; 2AG is the CPU 315-2 DP.
• 14 — the functional version. This is the number people ignore and should not. A -0AB0 part with functional version 13 and one with 14 differ in firmware baseline and sometimes in supported I/O; the higher number is generally a functional superset, but not always, and a machine program compiled against a specific CPU version can refuse to load on a different one.
• -0AB0 — packaging and variant. 0AB0 is the standard single unit.

Where the traps are

Spaces and hyphens are cosmetic. 6ES7315-2EH14-0AB0, 6ES7 315-2EH14-0AB0 and 6ES7315 2EH14 0AB0 are the same article. Any search worth using normalises them; ours does.

The functional version is not optional. Buying “a 315-2 PN/DP” without the 14 can get you a part that will not run the program you have. When a supplier lists a part without the last blocks, ask for a photo of the rating plate before ordering.

SIPLUS is a different article. A 6AG1 number is the SIPLUS version of a standard 6ES7 article: conformal-coated and rated for a wider temperature range. Its Siemens product page names the standard article it is based on, and the final blocks of the two numbers often differ, so do not expect a character-for-character match. The two are generally functionally equivalent, but the price and the environmental rating differ substantially. A supplier offering a 6AG1 against a 6ES7 request should say so.

“-0AB0” is not always “-0AB0”. Some families use the final block for bundle variants (with or without memory card, with or without front connector). Check what is in the box.

Refurbished parts may carry an older functional version. This is normal on the surplus market and usually fine; it is a problem only when your project is version-locked. What each condition grade means is set out in the guide to conditions.

Using the number to search

The practical workflow is: type the number with or without spaces, look at what comes back, and check three things on the part page before you request a quote — the functional version matches, the lifecycle status is what you expected, and the suppliers offering it list a condition you can accept. Whether two numbers are interchangeable is settled on the article’s Siemens product page, which shows its lifecycle status and, where one exists, its successor.

If the number on your drawing returns nothing, it is usually one of three things: a legacy number that has been superseded, an ordering code for a configured assembly rather than a single article, or a distributor’s own SKU. All three are worth searching anyway — cross-reference tables map many of them — and if nothing matches, a request with the number and a photo of the plate will usually be identified by a supplier who carries the family. The guide to RFQs explains how to write a request that gets answered.

Sources

Links checked on 13 October 2026.

• Siemens: structure of the 16-digit ordering number (MLFB) for SIMOTICS low-voltage motors: Siemens’ own explanation of one number scheme, which states that it does not cover every possible combination and refers to the catalogue and configuration tools.
• Siemens SiePortal: 6ES7315-2EH14-0AB0: the product page for the CPU decoded above, with its lifecycle status.