Upgrading S7-400H CPU 417-4H to CPU 410-5H with F-Safety: Backplane Compatibility, Fiber Sync, and SEC Sizing

Yes, existing S7-400H backplane racks (such as UR2-H or dual UR1/UR2 racks) can be 100% reused when upgrading an AS 417-4H to a CPU 410-5H with F-Safety in SIMATIC PCS 7 V8.2. Safety operation does not mandate rack replacement. However, three critical hardware and licensing changes are mandatory: the existing optical sync submodules must be replaced with CPU 410-specific sync submodules (6ES7960-1AA08-0XA0), each CPU 410-5H requires a dedicated System Expansion Card (SEC) sized to the facility's required Process Object (PO) count (e.g., 6ES7653-2BA00-0XB0 for 2,600+ PO), and a separate Safety Matrix / F-Runtime license must be provisioned.

Hardware Migration Strategy: Replacing CPU 417-4H with CPU 410-5H

Facilities running mature SIMATIC PCS 7 systems frequently hit memory and performance limits on older S7-400H controllers (such as CPU 417-4H 6ES7417-4HT14-0AB0 or 6ES7417-4XT05-0AB0). When upgrading to PCS 7 V8.2 or V9.x, the SIMATIC PCS 7 CPU 410-5H Process Automation (6ES7410-5HX08-0AB0) serves as the universal replacement.

Engineers facing tight turnaround outages often ask whether the existing physical backplane racks can be preserved while performing a rapid CPU swap, particularly when integrating Fail-Safe (F-Safety) functionality.

Backplane Compatibility: Reusing UR2-H and UR1/UR2 Racks

According to the official CPU 410-5H Process Automation System Manual:

Full Backplane Compatibility: The CPU 410-5H utilizes the standard S7-400 physical form factor and backplane bus (P-bus and K-bus). It mounts directly into existing UR2-H split redundant racks (6ES7400-2JA00-0AA0) or dual independent UR1 (6ES7400-1TA01-0AA0) / UR2 (6ES7400-1JA01-0AA0) racks.
Safety Functionality: Fail-safe operation in PCS 7 (using S7 F-Systems and Safety Matrix) is purely software- and communication-driven (PROFIsafe protocol). Fail-safe operation does not require specialized backplane racks.

Mandatory Hardware Replacements: Sync Submodules and Power Supplies

While the rack and I/O cards can be reused, specific components cannot be transferred from the CPU 417-4H:

Optical Sync Submodules: The synchronization submodules used on older CPU 417-4H controllers (e.g., 6ES7960-1AA04-0XA0 or 6ES7960-1AA06-0XA0) are incompatible with CPU 410-5H. You must install the dedicated CPU 410 sync submodules:

Short-range up to 10 m: 6ES7960-1AA08-0XA0 (requires 2 per CPU, total 4 for a redundant pair).
Long-range up to 10 km: 6ES7960-1AB08-0XA0.

Power Supply Capacity: The CPU 410-5H consumes higher backplane current during dual PROFINET operation. Ensure existing power supplies (e.g., PS 407 10A 6ES7407-0KA02-0AA0 or PS 407 20A) have sufficient capacity margin.

System Expansion Card (SEC) Sizing and Licensing Guardrails

Unlike CPU 417-4H, which used physical RAM/Flash memory cards to expand work memory, the CPU 410-5H features a single, universal hardware CPU where processing capacity is unlocked exclusively via the System Expansion Card (SEC):

SEC Mandatory Unit: The CPU 410-5H cannot boot without an SEC inserted. The SEC sets the maximum number of Process Objects (PO) the controller can execute.
SEC Sizing Tiers: SECs are available in distinct PO packages: 100 PO, 500 PO, 1,000 PO, 1,600 PO, and 2,600+ PO (PO 2k+).
F-Safety Licensing: To enable fail-safe CFC charts, the controller must have an active F-Runtime License (6ES7653-2CX00-0XB0 or 6ES7653-2CX01-0XB0). In redundant H-systems, a separate F-license is required for each CPU.

CPU 417-4H vs CPU 410-5H Technical and Architecture Comparison

The following table compares specifications and upgrade requirements between CPU 417-4H and CPU 410-5H:

Technical AttributeLegacy AS 417-4HModern CPU 410-5HMigration Requirement / ImpactCompatible Backplane RacksUR1, UR2, UR2-HUR1, UR2, UR2-H100% Reusable (Zero rack rewiring)Sync Submodule MLFB6ES7960-1AA04/06-0XA06ES7960-1AA08-0XA0Must purchase 4 new sync modulesMemory Expansion MediumPhysical RAM Card (e.g. 16MB)System Expansion Card (SEC)SEC determines PO capacity; no RAM cardIntegrated PROFINET PortsNone (Requires CP 443-1)2 Ports (Integrated 100/1000 Mbit)Eliminates external Ethernet CPsF-Safety CompatibilityS7 F-Systems V6.xS7 F-Systems V6.1+ / V6.2Dedicated F-Runtime license per CPUMax Execution Speed~18 ns per binary op~10 ns per binary opUp to 3x faster program execution

Verification

Verify the hardware upgrade through the following steps:

Insert the SECs and sync submodules into both CPU 410-5H processors. Mount them into the UR2-H rack.
Connect fiber-optic sync cables crosswise (Upper to Lower, Lower to Upper). Power up the rack.
Verify that the RUN LED lights green on Master CPU 0 and RUN lights green on Standby CPU 1 with REDF extinguished.
In SIMATIC Manager HW Config, update the station hardware definition to CPU 410-5H with the correct firmware and SEC PO tier.
Download the hardware configuration. Open Module Information; confirm that PO utilization is within SEC limits and redundancy coupling indicates 'Redundant mode'.

Limitations and Operational Precautions

Consider these operational rules when upgrading to CPU 410-5H:

Never Power Up Without SEC: Attempting to boot a CPU 410-5H without an SEC card inserted causes a persistent DEFECT LED fault; the card must be seated before powering the rack.
Fiber Cable Handling: Ensure single-mode vs multi-mode fiber patch cables match the sync submodule optics (standard 6ES7960-1AA08-0XA0 uses multi-mode 50/125 µm or 62.5/125 µm duplex cables).
Commercial Disclaimer: Commercial Accuracy Disclaimer: Software order numbers (MLFBs), package structures, and hardware capacity prerequisites vary across PCS 7 versions and hardware platforms. System integrators must confirm exact software entitlements and licensing requirements against the official Siemens Catalog CA 01 and obtain an authorized Siemens distributor quotation prior to purchasing.