Replacing CPU 410-5H with Same Model and Higher Firmware - SEC Transfer and PO Management

Replacing a SIMATIC PCS 7 CPU 410-5H (6ES7410-5HX08-0AB0) with a spare unit possessing higher firmware (e.g., V8.2 replacing V8.0) is fully supported without altering the existing STEP 7 HW Config version, as CPU 410 firmware is backward-compatible. Before replacing the controller, execute a CFC parameter readback to preserve tuned runtime parameters and book back the AS Process Objects (POs) to the Engineering Station license database. Power down the subrack, transfer the existing System Expansion Card (SEC) or install the new 1000 PO SEC into the rear slot of the new CPU, power up, execute a memory reset (MRES), and perform a full download.

Hardware Sizing and System Expansion Card (SEC) Principles

The SIMATIC PCS 7 CPU 410-5H Process Automation controller (6ES7410-5HX08-0AB0) features a unified hardware architecture where controller memory and processing capacity are defined entirely by the System Expansion Card (SEC) inserted into the rear of the CPU. System Expansion Cards range from 100 PO (6ES7653-2CA00-0XB0) to unlimited PO (6ES7653-2CF00-0XB0).

In PCS 7 V8.1 and higher, PO expansion can be executed online using CPU 410 Expansion Packs (6ES7653-2CC00-0XB0) without power cycling. However, in legacy PCS 7 V8.0 installations, upgrading PO capacity often entails swapping the physical SEC card or replacing the CPU assembly with a pre-licensed unit.

Firmware Compatibility Across PCS 7 Releases

Siemens guarantees strict backward compatibility for CPU 410-5H firmware:

A CPU 410-5H loaded with modern firmware (such as V8.2.0 or V8.2.1) operates flawlessly in older PCS 7 versions (including PCS 7 V8.0 and V8.1).
No HW Config Change Required: In the STEP 7 HW Config catalog, the CPU can remain configured under its original V8.0 hardware object definition. The V8.2 physical controller executes the V8.0 configuration transparently without requiring catalog updates or STEP 7 upgrades.
Redundant System Rule: In redundant AS 410-5H systems, both CPU 410 controllers in the fault-tolerant subrack must run the identical firmware release to support redundant coupling and synchronization.

Pre-Replacement Engineering Prerequisites

Before physically de-energizing the controller rack, the following software data preservation steps are mandatory:

Read Back CFC Runtime Parameters:
- Open SIMATIC Manager and navigate to the AS Chart folder.
- Select Chart > Read Back....
- Choose OCM-capable attributes and Designated parameters.
- This saves operator-tuned PID parameters, alarm limits, and manual setpoints from the controller RAM back into the offline CFC project.
Book Back AS Process Objects:
- In SIMATIC Manager, right-click the Chart folder and select Charts > Book Back Process Objects.
- This unbinds licensed POs from the old controller's serial number and returns the entitlements to the ES license pool in Automation License Manager (ALM).

Physical Replacement and Commissioning Procedure

Execute the hardware and commissioning replacement following this standardized procedure:

De-energize the Power Supply: Switch off the rack power supply module (e.g. PS 407 or PS 405).
Extract Existing CPU: Unlock the CPU ejector lever and slide the CPU 410-5H out of the UR2/CR3 rack.
Inspect and Insert System Expansion Card:
- Inspect the rear SEC slot of the replacement CPU.
- If transferring the existing SEC, transfer it into the rear slot until seated.
- If upgrading capacity, insert the new SEC (e.g. 1000 PO card 6ES7653-2CC00-0XB0).
Seat Replacement CPU: Insert the replacement CPU into the rack and lock the ejector lever.
Power On and Memory Reset (MRES):
- Energize the power supply module.
- Perform a manual memory reset by holding the CPU toggle switch in MRES position until the STOP LED flashes, release, and immediately turn to MRES again within 3 seconds.
Download Configuration and Programs:
- Download HW Config to the controller via MPI or Industrial Ethernet.
- Open CFC and perform a full compile and download (PLC > Download > Entire program).
- Book the required AS Process Objects to the new CPU via Charts > Book Process Objects.

Controller Replacement and Licensing Workflow

The table below summarizes the operational actions and licensing impacts:

Engineering PhaseMandatory ActionTool / Menu InterfaceLicensing / Data ImpactPreparationRead Back CFC ParametersChart > Read Back...Prevents loss of tuned setpoints and PID gainsLicense ProtectionBook Back Process ObjectsCharts > Book Back Process ObjectsRestores AS RT POs to ES license poolHardware SwapTransfer or Upgrade SECPhysical rear slot of CPU 410Determines maximum available controller PO capacityInitializationPerform MRES on CPUPhysical Mode Selector ToggleClears internal work memory; resets diagnostic bufferCommissioningDownload HW & Full CFCSIMATIC Manager / CFCInstantiates program logic matching offline projectFinal LicensingBook POs to New CPUCharts > Book Process ObjectsValidates CPU SEC capacity against consumed chart POs

Verification

Verify correct operation of the replacement CPU:

Check the CPU front diagnostic LEDs: confirm RUN LED is solid green and STOP, INTF, and EXTF are extinguished.
Open PLC > Diagnostic/Setting > Module Information in SIMATIC Manager. Confirm CPU firmware displays the new revision (e.g. V8.2.0) and operating mode reports RUN.
Open the Performance tab in Module Information. Confirm the maximum PO capacity matches the installed SEC (e.g. 1000 PO).
Verify that cyclic communication with distributed I/O stations (ET 200M/ET 200SP) is active and fault-free.
Confirm WinCC OS Server establishes cyclic data exchange with the controller.

Limitations and Operational Precautions

Review the following technical limitations during controller maintenance:

SEC Hot-Plugging Strictly Prohibited: The System Expansion Card must NEVER be inserted or removed while the CPU is powered. Removing the SEC under voltage causes immediate controller stop and permanent card damage.
Redundant Firmwares Must Match: In redundant S7-400H / AS 410-5H systems, running different firmware revisions between partner CPUs is permitted only temporarily during online firmware updating. Permanent operation requires identical firmware.
Commercial Procurement Guardrail: Sizing controller PO capacity requires exact Siemens order numbers. Always verify the SEC card MLFB (6ES7653-2Cxxx-0XB0) against the authorized Siemens Industry Mall catalog.

Engineer FAQ

Do I need to upgrade my STEP 7 HW Config when installing a CPU 410 with newer firmware?

No. CPU 410-5H firmware is fully backward compatible. A CPU with V8.2 firmware can execute a HW Config compiled for V8.0 without any modifications in the offline project.

What happens if I forget to perform a parameter readback before swapping the CPU?

If you do not read back parameters, any setpoint adjustments, controller tuning gains, or alarm limits modified from the WinCC OS faceplates since the last compile will be lost and replaced with the offline initial values.

Can I upgrade the Process Objects of a CPU 410-5H without replacing hardware?

Yes, starting in PCS 7 V8.1, you can use CPU 410 Expansion Packs (6ES7653-2CC00-0XB0) to upgrade PO capacity online without stopping the CPU or replacing the physical SEC.