Programming and Configuring the Siemens SIMATIC CPU 412-5H (6ES7412-5HK06-0AB0) with STEP 7 V5.5
The SIMATIC CPU 412-5H is the entry-level redundant controller of the SIMATIC S7-400H (Hochverfügbar / high-availability) family. The order number 6ES7412-5HK06-0AB0 identifies the FW V6.0 hardware release that runs only inside the legacy STEP 7 V5.x environment or inside PCS 7. TIA Portal, from V13 through the current V19, does not expose S7-400H CPUs in its hardware catalog and will not let you build a fault-tolerant station with them. This reference explains why the TIA path is closed, which toolchain is correct, how to register the HSP so the catalog shows 6ES7412-5HK06-0AB0, and how to commission the redundant pair end-to-end.
1. CPU 412-5H at a Glance
The CPU 412-5H belongs to the H-CPU lineup launched as the lower tier for fail-safe, hot-standby process applications. Two of these CPUs are mounted in a single UR2-H rack (or split across two UR2 racks with redundant IM 460-3 / IM 461-3 receivers), connected via fiber-optic sync modules, and operated as one logical controller.
| Parameter | CPU 412-5H (6ES7412-5HK06-0AB0) |
|---|---|
| MLFB | 6ES7412-5HK06-0AB0 |
| Firmware release | V6.0 (suffix K06 in the MLFB) |
| Work memory (code + data) | 512 KB + 512 KB |
| Bit instruction time | ~75 ns |
| Integrated PROFINET interface | 1 × PN IO, 2-port switch |
| Integrated PROFIBUS DP interface | 1 × DP master/slave |
| Sync module slots | 2 (front of CPU) |
| Sync fiber length | Up to 10 m with default FO cables; up to 10 km with SFP modules in IF modules |
| Required configuration tool | STEP 7 V5.5 SP4 or higher (PCS 7 V8.x / V9.x also accepted) |
| TIA Portal support | None — not cataloged |
Verify the exact FW and bundle on the front of the module or via the Siemens Industry Online Support catalog page: 6ES7412-5HK06-0AB0 product entry. The datasheet linked from the catalog page is the authoritative source for tool version, firmware bundle, and supported HSPs.
2. Why TIA Portal Cannot Configure the S7-400H
Siemens deliberately excluded the S7-400H family from the TIA Portal hardware catalog. The official product note that documents this exclusion is entry 84047138 in the Siemens Industry Online Support portal. Search it under the title "Which modules are supported in TIA Portal?" or "SIMATIC S7-400/S7-400H in TIA Portal". The matrix in that KB lists every order number of the S7-300, S7-400, and S7-400H families and explicitly marks S7-400H CPUs as "not in TIA Portal".
Three technical reasons are stated in Siemens documentation and reinforced by the TIA Portal "Options" installation dialog:
- Redundancy data model: The H-station configuration requires paired slots, duplicated sync modules, H-specific OB mapping (OB 70, OB 72, OB 80-H, OB 82-H, OB 83-H, OB 85-H, OB 86-H, OB 87-H, OB 88-H, OB 90-H, OB 121-H, OB 122-H) and master/standby status bits that TIA Portal never modelled for S7-400.
- HSP dependency: TIA Portal only ships the HSPs it expects to support. The S7-400H-specific HSP (HSP 2021, HSP 2031, etc.) is delivered exclusively for STEP 7 V5.5 and is not registered against the TIA Hardware Support Package catalog.
- Lifecycle decision: S7-400H is positioned as a mature, long-lived process platform. Siemens directs new installations to PCS 7 V9.x, which still uses the STEP 7 V5.5 project kernel under the hood. New automation projects are steered toward AS 410 / AS 410-H (which is a SIMATIC S7-410, not S7-400) for TIA Portal-native redundancy.
As a direct consequence, the Hardware Catalog in TIA Portal V13, V13 SP1, V13 SP2, V14, V14 SP1, V15, V15.1, V16, V17, V18, and V19 does not contain entries for 6ES7412-5HK06-0AB0 (or any other 6ES7412-5Hxxx or 6ES7416-xxx variant). Attempting to insert a "generic" S7-400 CPU and patch the MLFB will be rejected by the device validation routine, and the slot will not compile.
3. Required Toolchain
| Tool | Minimum version | Recommended version | Purpose |
|---|---|---|---|
| STEP 7 V5.5 + SP | V5.5 SP4 | V5.5 SP4 + HF11 or later, or V5.6 (if licensed) | Project creation, hardware config, S7 program |
| PCS 7 | V8.0 SP1 | V9.0 SP2 | CFC / SFC / OS engineering when paired with WinCC |
| S7-PCT (Port Configuration Tool) | V3.5 | V3.5.4 | PN port topology, port statistics for H station PN ring |
| SIMATIC PDM | V8.2 SP1 | V9.0 | PROFIBUS / PROFINET device parameterization in H station |
| SIMATIC Automation Tool | V3.0 | V4.x | FW update, certificate handling (alternative to TIA "Online & Diagnostics" tools, which do not exist for H) |
STEP 7 V5.5 is sold as a DVD package or as a download under the order number 6ES7810-5CC13-0YA5 (STEP 7 V5.5 SP4 / 2010). The "2010" variant ships the latest HSP set that contains the 6ES7412-5HK06 CPU. Verify in Start > Simatic > Information > Installed software that the STEP 7 revision is at least K5.5.4.0.
4. Adding the 6ES7412-5HK06-0AB0 to the STEP 7 V5.5 Hardware Catalog
If the catalog view does not list the CPU, the Hardware Support Package (HSP) is missing. Two methods are valid: install the bundled HSP from the STEP 7 DVD, or load a newer HSP from Siemens support.
4.1 Install the HSP from DVD
- Insert the STEP 7 V5.5 installation DVD (or mount the ISO image).
- Browse to
DVD:\STEP7\HSP\HSP_xxxx.exeand run as administrator. - The HSP setup installs into
C:\Program Files\Siemens\Automation\STEP7\S7HWSP\. - Open SIMATIC Manager. Choose Options > Install HW Updates. Wait for "Installation completed".
- Close and reopen SIMATIC Manager.
- Open HW Config; the catalog now lists 6ES7412-5HK06-0AB0 under SIMATIC 400 > CPU 400H > CPU 412-5H.
4.2 Install a newer HSP from Siemens support
- Go to Entry 23183356 — Hardware Support Packages for STEP 7 V5.5 / V5.6.
- Download the latest
S7HSP5xxx.exerelevant to your STEP 7 revision. - Run the executable. The HSP unpacks and auto-registers with STEP 7.
- In SIMATIC Manager, run Options > Install HW Updates once more so the new HSP is merged with the catalog database.
4.3 Verify catalog registration
In HW Config, navigate to SIMATIC 400 > CPU-400H > CPU 412-5H. The right pane should list the variants:
- 6ES7 412-5HK06-0AB0 — V6.0.0
- (Older FW releases from the same HW release — same MLFB — may show under additional version entries after a fresh HSP install.)
Double-click the entry; the slot dialog opens. The dialog exposes the H-specific tabs (Redundancy, Diagnostics, Synchronization, Time-of-Day) that confirm the CPU is correctly registered as an H-type controller.
HKEY_LOCAL_MACHINE\SOFTWARE\Siemens\Automation\STEP7\HWSP; restricted user rights prevent the registry merge and the CPU silently disappears from the catalog.
5. Building an H-Station in HW Config
Unlike a non-redundant S7-400 station, the H-station is a fixed, two-CPU arrangement. STEP 7 V5.5 supports two rack layouts:
- UR2-H rack (single rack with redundant slots) — preferred for cabinet-mount with both CPUs side-by-side and short FO sync cables.
- UR2 + UR2 split (two racks coupled via IM 460-3 / IM 461-3) — preferred for physically separated plants (e.g., redundant control rooms, geographically distributed). Max 100 m of backplane distance between IM 460-3 and IM 461-3.
5.1 Insert the rack
- In HW Config, drag RACK-400 > UR2-H (or two UR2 racks if split) into the project window.
- Slot 1 is reserved for the power supply; slot 3 is the first usable CPU slot.
- Drag SIMATIC 400 > CPU-400H > CPU 412-5H > 6ES7 412-5HK06-0AB0 into slot 3.
- To build the redundant pair, click on the slot, choose Insert > Redundancy partner. STEP 7 automatically places the partner CPU in slot 3 of the redundant rack.
- Insert sync modules (6ES7960-1AA06-0XA0, or 6ES7960-1AB06 for long-distance) into the front slots of both CPUs. HW Config logs a configuration error if the sync modules are absent.
5.2 Insert PROFIBUS / PROFINET
The CPU 412-5H has one DP and one PN port. To create a fully redundant PROFINET ring:
- Right-click the PN interface of the master CPU and choose Properties > Subnet > New PROFINET subnet.
- Repeat for the partner CPU on a second subnet.
- Insert the ET200M stations (IM 153-4 PN HF for 200HF redundancy mode) or ET200SP stations (IM 155-6 PN HF) twice — once on each subnet — and assign device numbers 1..n.
- Configure both PN interfaces of every remote I/O station as Switched and wire the ring so the topology closes.
This double-attached I/O pattern is the foundation of S7-400H availability. With both PROFINET networks healthy the IO is processed by the master CPU; if one network fails, the standby CPU takes over the IO via the surviving subnet within the configured switchover time (typical: 100–500 ms).
6. Redundancy-Specific Parameters
The CPU's Properties dialog contains a Redundancy tab with the following controls:
| Parameter | Field / value | Description |
|---|---|---|
| Sync module addresses | Slot-pair 0 (left), 1 (right) | Default — only change for two-rack split configurations. |
| Standby-master swap | Enabled / Disabled | Enabled swaps the role of master and standby after every cold restart, useful for equal aging. |
| Max cycle-time increase | 0–100 % | Compensation factor applied when standby synchronizes. |
| OB 70 / OB 72 handling | Per channel / per station | Selects whether I/O redundancy loss is reported per channel or per station. |
| Self-test during startup | Standard / Reduced | Reduced shortens startup time but disables some diagnostics. |
| Watchdog time | 20–65535 ms | Maximum tolerated sync loss before forced failover. |
The Synchronization tab exposes:
- Number of redundant partner CPUs: 1 for standard H, more for redundant H systems.
- Type of synchronization: Sync via fiber-optic cable or sync via backplane (only when both CPUs are in the same UR2-H rack).
- Update of the standby: Cyclic vs. event-driven.
7. Synchronization Modules and Fiber-Optic Links
Sync modules plug into the front of the CPU and convert the internal parallel sync data to a serial differential signal on a fiber pair. The standard parts are:
| Sync module | Max cable length | Fiber type | Use case |
|---|---|---|---|
| 6ES7960-1AA06-0XA0 | 10 m | POF (plastic optical fiber) | Cabinet-internal redundancy |
| 6ES7960-1AB06-0XA0 | 250 m | PCF (HCS fiber) | Adjacent cabinets |
| 6ES7960-1AC06-0XA0 | 10 km | Glass mono-mode (with SFP) | Geographically separated plants |
Connect module slot "0" of CPU 0 to module slot "0" of CPU 1, and the same for slot "1". Cross-over is not required — the modules are internally crossed. Both channels must be healthy for full redundancy; a single-channel link still operates, but the system logs the loss of one synchronization path in OB 72.
8. Firmware Versions and Compatibility
The MLFB 6ES7412-5HK06-0AB0 is the V6.0 release of CPU 412-5H. STEP 7 V5.5 SP4 or higher recognizes it. Downgrading firmware below V6.0 on a K06-hardware CPU is not possible. The recommended sequence for an H-CPU firmware update:
- Download the FW file
S7-400H_CPU_412-5H_V06_xx.updfrom Siemens support. - In STEP 7 V5.5, establish an online connection to one CPU. The other CPU must be in STOP or in standby to avoid split-brain behavior during the update.
- Choose PLC > Update Firmware and select the .upd file.
- Wait for the success message. Repeat on the partner CPU.
9. Common Errors and Field Troubleshooting
| Symptom | LED on CPU | Likely root cause | Corrective action |
|---|---|---|---|
| "Module not found in catalog" | N/A (engineering issue) | HSP not installed or STEP 7 older than SP4 | Install latest HSP from entry 23183356, restart SIMATIC Manager |
| CPU in STOP, IFM LED red | IFM red, RUN off | Sync modules missing or fiber cable damaged | Inspect sync module seating, replace POF cable, check Redundancy diagnostic buffer |
| Standby CPU keeps restarting | STBY LED flashing | Different firmware versions on master and standby | Update the standby CPU to match master FW; reboot |
| PROFINET IO fails on both rings | BF (bus fault) on PN interface | Device names not assigned to redundant devices | Use S7-PCT to assign PROFINET device names to both ports of every HF IM station |
| OB 72 (redundancy loss) reported on every cycle | EXTF red | Standby CPU in run-up state; topology of ring incomplete | Wait for standby to reach RUN; check that the ring is closed by S7-PCT topology scan |
| TIA Portal "Unknown device" warning when importing S7 V5.5 project | N/A | TIA Portal cannot import S7-400H station | Keep the H-station in STEP 7 V5.5; export as .s7p file; do not migrate |
10. Migration Paths Away from STEP 7 V5.5
Engineers facing the end of Windows 10 support or Windows 11 hardening rules for STEP 7 V5.5 have three options:
- Stay on STEP 7 V5.5 + virtual machine: Install STEP 7 V5.5 SP4 inside a Windows 7 / Windows 10 x64 VM (e.g., VMware Workstation) on a hardened host. Siemens documents the supported hypervisor matrix in the PCS 7 V9.0 SP3 readme.
- Migrate to PCS 7 V9.x: PCS 7 V9.x uses the same STEP 7 V5.5 kernel, so the H-station can be opened and edited. CFC/SFC programs remain valid. WinCC V7.5 OS panels can be reused.
- Migrate to AS 410-H (S7-410): This is the only TIA Portal-native redundant platform. Hardware is different (ET 200SP HF, F-CPU 410-5H), and a full functional migration including the safety case is required.
Option 1 is the lowest risk when the existing S7-400H station is mature. Option 3 is the strategic choice for new plants where the H-CPU is reaching its declared spare-part end and a TIA Portal toolchain is mandated.
11. Verification and Acceptance Test
After configuration, perform this checklist before handover:
- Save and compile HW Config. The right pane shows "No errors" for every slot.
- Download hardware configuration to both CPUs.
- Bring both CPUs to RUN. Confirm the STBY LED is solid on the standby CPU.
- Open PLC > Module Information > Redundancy. Verify the fields "Status of the redundant system = OK" and "Master/Standby role correctly assigned".
- Pull the power on the master CPU. Observe that the standby CPU becomes master within the configured watchdog time and the process continues without OB 85 stop.
- Restore power to the failed CPU. Confirm it returns as standby within 30 s and resynchronizes without disturbance.
- Open S7-PCT and scan the topology. Confirm the PROFINET ring is closed and no device is in "Not reachable".
- Sign the FAT/SAT documents with the diagnostic buffer log attached.
12. Frequently Asked Questions
Can I configure a Siemens CPU 412-5H in TIA Portal V13 Update 1?
No. TIA Portal V13 Update 1 and every subsequent TIA release (V14 SP1, V15, V15.1, V16, V17, V18, V19) omit S7-400H CPUs from the hardware catalog. Configure the 6ES7412-5HK06-0AB0 in STEP 7 V5.5 SP4 or higher, or in PCS 7 V8.x / V9.x.
How do I make the 6ES7412-5HK06-0AB0 visible in the STEP 7 V5.5 hardware catalog?
Install the latest Hardware Support Package from entry 23183356, then run Options > Install HW Updates inside SIMATIC Manager. Restart HW Config — the CPU now appears under SIMATIC 400 > CPU-400H > CPU 412-5H.
What is the minimum STEP 7 version for the 6ES7412-5HK06-0AB0 firmware V6.0?
STEP 7 V5.5 SP4 with the matching HSP. Older STEP 7 V5.5 SPs do not include the K06 HW release; the catalog entry either does not exist or compiles with a "not supported" warning.
Which sync fiber-optic cable should I order for an H-station inside one cabinet?
Use the 6ES7960-1AA06-0XA0 sync module plus a POF cable (up to 10 m). For cabinet-to-cabinet distances up to 250 m, replace with the 6ES7960-1AB06-0XA0 module and PCF cables. For distances up to 10 km, use the 6ES7960-1AC06-0XA0 module with mono-mode glass fiber and SFPs.
Is it possible to migrate a STEP 7 V5.5 S7-400H project to TIA Portal?
No. TIA Portal refuses S7-400H stations during import and will not create a usable H-station. Either stay on STEP 7 V5.5 (or PCS 7 V9.x, which uses the same kernel) on a supported Windows OS, or plan a hardware migration to AS 410-H (SIMATIC S7-410) for a TIA Portal-native path.