In this guide
Siemens identifies every product with an order number, also called the MLFB. A number such as 6ES7 313-5BG04-0AB0 looks like noise, but the first block alone tells you a lot about what you are holding.
The structure of a 6ES7 number
Siemens order numbers are written in blocks separated by spaces and dashes. Using 6ES7 313-5BG04-0AB0 as an example:
- 6ES7 identifies the product family: SIMATIC S7 and related hardware
- 313 points to the module type within that family. Here it is a CPU 313C
- 5BG04 identifies the variant and its version
- 0AB0 carries version and packaging information
Copy all of it. Two numbers that differ only in the last block can still differ in hardware or firmware support, so treat the whole string as one identifier.
What the first digits after 6ES7 tell you
| First digits | Typical family |
|---|---|
| 6ES7 21 to 23 | S7-1200, or the older S7-200 |
| 6ES7 288 | S7-200 SMART |
| 6ES7 3 | S7-300 |
| 6ES7 4 | S7-400 |
| 6ES7 5 | S7-1500 and ET 200MP |
| 6ES7 1 | ET 200 distributed I/O |
This is a guide, not a complete catalogue, and the numbering has exceptions. The product name printed on the label settles any doubt.
Other common Siemens prefixes
| Prefix | What it is |
|---|---|
| 6AV2 / 6AV6 | HMI operator panels |
| 6SL3 | SINAMICS drives |
| 6SE6 | MICROMASTER 4 drives |
| 6EP | SITOP power supplies |
| 6GK | Networking and communication |
| 3RT / 3RV / 3RW | SIRIUS contactors, motor protection and soft starters |
Why the version still matters
Even with the right order number, check the hardware and firmware version on the module. A CPU's firmware decides which engineering software version can load a project into it. Replacing a CPU with a different firmware version may need a newer software release or a firmware change.
What to send us
- The full order number typed out, plus a clear photo of the label
- The firmware or version marking on the front or side
- The quantity and whether the machine is down
If a Siemens part number is not in our list, send it anyway. The identifier covers common prefixes only.