The 6ES7314-6BH04-0AB0 is one of the most requested spare-part numbers in the Siemens SIMATIC S7-300 family — and one of the most misunderstood. This guide is written for maintenance engineers and buyers who need to know exactly what this CPU is, what it can do, and how to source it now that the S7-300 line is discontinued.
Introduction
Order a part number without checking the last digits, and you can end up with a CPU that lacks the network interface your machine was built around. The 6ES7314-6BH04-0AB0 sits in a family of visually identical compact CPUs — the 314C-2 PtP, 314C-2 DP, and 314C-2 PN/DP — that differ precisely in their communication hardware. Getting the identification right is the first half of the job; the second half is finding genuine stock for a discontinued part. This guide covers both.
What Is the 6ES7314-6BH04-0AB0?
The 6ES7314-6BH04-0AB0 is a SIMATIC S7-300 compact CPU, type CPU 314C-2 PtP. Siemens’ own datasheet identifies it as a compact CPU with integrated I/O, an MPI port, and an RS485 point-to-point (PtP) interface. It belongs to the “C” (compact) class of CPU 314 variants, which integrate digital and analog I/O directly on the module — unlike the standard CPU 314, which requires separate signal modules for any I/O.
Decoding the article number helps avoid the most common ordering error:
- 6ES7314-6BH04-0AB0 = CPU 314C-2 PtP (MPI + RS485 point-to-point) — this article
- 6ES7314-6CH04-0AB0 = CPU 314C-2 DP (MPI + PROFIBUS DP master/slave)
- 6ES7314-6EH04-0AB0 = CPU 314C-2 PN/DP (MPI/DP + PROFINET)
The mechanical dimensions, I/O count, and memory are identical across all three — only the second interface differs. If you are replacing a failed CPU in an existing machine, read the nameplate rather than relying on paperwork; our CPU 314 variant comparison walks through the differences in detail.
Key Specifications at a Glance
| Attribute | Value |
|---|---|
| CPU type | CPU 314C-2 PtP (compact) |
| Work memory | 192 KB |
| Integrated digital I/O | 24 DI / 16 DO |
| Integrated analog I/O | 5 AI / 2 AO |
| Interfaces | MPI + RS485 point-to-point (PtP) |
| Supply voltage | 24 V DC |
| Programming software | STEP 7 V5.5 SP1 or higher |
| Memory card | SIMATIC Micro Memory Card (MMC) required |
| Dimensions / weight | 120 × 125 × 130 mm, approx. 680 g |
These figures follow Siemens’ technical documentation for the CPU 31xC series; the work memory and I/O counts are the ones that matter most when checking compatibility with an existing program.
Hardware Design and Integrated I/O
The “C” in 314C is the module’s real selling point for small machines: the CPU carries its own process I/O, so a complete control system can fit on a single S7-300 rail without signal modules. The 24 digital inputs and 16 digital outputs operate at 24 V DC, and the 5 analog inputs / 2 analog outputs handle standard 0–10 V or 4–20 mA signals. Integrated functions — counting, frequency measurement, and PID control — run directly on the module, offloading the cycle from programmed equivalents.
Power comes from a 24 V DC supply, and a SIMATIC Micro Memory Card is mandatory: the CPU has no internal load memory of its own, so no MMC means no program. Keep the original MMC with the failed CPU — the replacement CPU ships empty, and the program must be transferred from backup.
Communication: MPI and the Integrated PtP Interface
Two communication interfaces define this variant. The MPI port handles programming, HMI panels, and communication with other SIMATIC devices on a small network. The RS485 point-to-point interface speaks ASCII, 3964(R), or RK 512 protocols — the reason this CPU exists. It connects directly to serial devices such as barcode readers, weigh scales, modems, and third-party controllers without a communication processor.
If your application instead needs PROFIBUS DP to talk to distributed I/O or drives, this is the wrong variant — you want the 6CH04 (DP) or 6EH04 (PN/DP). Converting a PtP machine to a DP network is not a firmware change; it is a hardware and program change.
Programming and Configuration Requirements
The CPU is programmed with STEP 7 V5.5 SP1 or higher in the classic SIMATIC Manager environment — the TIA Portal does not support the S7-300 compact CPUs of this generation. Programs transfer to the CPU over MPI via a PC adapter. This has a practical consequence for buyers today: the engineering stations still running this toolchain are themselves aging, which is one more argument for planning a migration rather than an indefinite series of like-for-like spares.
Typical Applications
The 314C-2 PtP was built for stand-alone machines that need modest I/O plus one serial device. Typical installations include packaging machines with serial weigh-scale interfaces, labeling and printing stations, small conveyor systems with barcode readers, and test benches logging data over a serial link. Its combination of integrated I/O and a free serial protocol made it a favorite of OEMs building the same machine for customers with different field devices — swap the PtP telegram definition, keep everything else.
Product Status: Discontinued and What Replaces It
Siemens has cancelled the 6ES7314-6BH04-0AB0 as a regular product; it survives on the market as a spare part, and Siemens’ official designation for the CPU is “spare part; product cancellation.” New-production stock is finite, refurbished and surplus channels carry an increasing share of supply, and prices follow accordingly.
Siemens’ designated successor platform is the S7-1500 series — a CPU 1511 or 1513 covers the processing load of a 314C comfortably, with TIA Portal replacing STEP 7 and a serial-module option (CM PtP) reproducing the point-to-point functionality. Migration is a project, not a swap: the program, the HMI, and the serial configuration all move to new tooling. In our experience servicing S7-300 fleets, the pragmatic rule is this: if the machine has years of life left and the serial device is business-critical, budget the S7-1500 migration now rather than after the last spare fails. For other CPUs in the same rack family, ouke’s CPU 315-2 AG10 replacement guide covers the same lifecycle questions for a larger sibling.
Where to Source the 6ES7314-6BH04-0AB0
For a discontinued spare, three checks separate a safe purchase from an expensive problem. First, verify the full article number including the “-6BH04-” block — the PtP, DP, and PN/DP variants are not interchangeable. Second, insist on nameplate or serial verification before payment; sellers of genuine surplus can provide it without hesitation. Third, confirm the firmware version, since the program on your MMC may require a minimum version to load.
ouke stocks tested 6ES7314-6BH04-0AB0 units with verification photos before shipment and a warranty on every CPU — see the current 6ES7314-6BH04-0AB0 product page for stock status. Related S7-300 hardware, including the PS307 power supply module that powers this CPU, is available from the same inventory.
FAQ
What CPU is the 6ES7314-6BH04-0AB0?
It is a SIMATIC S7-300 compact CPU, the CPU 314C-2 PtP, with integrated I/O, an MPI port, and an RS485 point-to-point interface.
What is the difference between 6BH04, 6CH04, and 6EH04?
They are three interface variants of the same compact CPU: 6BH04 has MPI + RS485 PtP, 6CH04 adds PROFIBUS DP, and 6EH04 adds PROFINET on top of DP. Memory and I/O are identical.
Which software programs the 6ES7314-6BH04-0AB0?
STEP 7 V5.5 SP1 or higher in the SIMATIC Manager environment; TIA Portal does not support this CPU generation.
Is the 6ES7314-6BH04-0AB0 still manufactured?
No. Siemens lists it as a spare part following product cancellation; remaining supply comes from spare-part and refurbished channels.
What replaces the 6ES7314-6BH04-0AB0?
Siemens’ successor platform is the S7-1500 — a CPU 1511/1513 with a CM PtP serial module reproduces the functionality in TIA Portal.
Conclusion
The 6ES7314-6BH04-0AB0 is a capable compact CPU with a specific niche — integrated I/O plus a genuine serial interface — and its discontinuation makes correct identification and verified sourcing the two skills that matter now. Match the full article number to your nameplate, keep the MMC with your program safe, and treat every spare purchase as part of a longer migration plan toward the S7-1500.
ouke can verify, test, and ship a genuine 6ES7314-6BH04-0AB0 for your next maintenance window — check live stock on the product page or send our team your nameplate photo for a compatibility check before you order.
Related Sources
- https://support.industry.siemens.com/teddatasheet?format=pdf&mlfbs=6ES7314-6BH04-0AB0&language=en&caller=SIOS
- https://cache.industry.siemens.com/dl/files/906/12996906/att_70325/v1/s7300_cpu_31xc_and_cpu_31x_manual_en-US_en-US.pdf
- https://www.dcsmodule.com/6es7314-6bh04-0ab0-siemens-simatic-s7-300-cpu-314c-2-ptp_p24450.html