AS Runtime Process Object (AS RT PO) Consumption and Licensing Rules for Redundant CPU 410-5H

In SIMATIC PCS 7 utilizing redundant CPU 410-5H controllers, AS Runtime Process Objects (AS RT PO) involve two distinct licensing layers: Engineering Station software licenses and physical System Expansion Cards (SEC). In the Engineering Station software pool (ALM), AS RT POs are booked once per automation station; a redundant CPU pair constitutes a single AS station, consuming only the net PO count of the program (e.g. 200 POs). However, at the hardware controller level, BOTH CPU 410-5H processors must have an identical System Expansion Card installed capable of supporting the full PO volume (e.g., each CPU must be equipped with an SEC of at least 200 POs). Hardware capacities are never summed across redundant CPUs.

Two-Tier Licensing Framework of the CPU 410-5H Architecture

The SIMATIC PCS 7 CPU 410-5H (Process Automation) controller introduces an innovative hardware architecture where a single universal CPU module (6ES7410-5HX08-0AB0) covers all application performance tiers, from small utility units up to massive process units with 2,600+ Process Objects. Controller execution capacity is determined by a plug-in hardware token called the System Expansion Card (SEC).

Engineers frequently confuse software licensing with hardware capacity:

Licensing DimensionWhat It GovernsWhere It ResidesBooking Scope in Redundant PairAS RT PO (Software License)Total authorized automation logic across the multiprojectAutomation License Manager on Engineering StationBooked Once (200 PO total for redundant station)System Expansion Card (Hardware SEC)Maximum physical execution capacity of the CPU hardwarePhysical slot on CPU 410-5H front panelMandatory on Both CPUs (200 PO SEC on CPU A and 200 PO SEC on CPU B)

Understanding this distinction prevents costly procurement errors and prevents unexpected download rejections during plant commissioning.

Software AS RT PO Booking vs Hardware SEC Capacity

In SIMATIC PCS 7, a Process Object (PO) represents a technological block that generates alarms and operator interface elements (such as PIDConL, MotL, VlvL, MonAnL, or user FBs configured with message capabilities). Channel drivers (Pcs7AnIn), logic gates (AND, OR), and mathematical functions consume zero Process Objects.

When compiling and downloading a program requiring 200 AS RT POs:

Engineering Station License Pool: SIMATIC Manager queries ALM on the ES. It checks whether the central pool has at least 200 available AS RT PO licenses. Because the redundant pair functions as a single logical controller station (SIMATIC 400(1)), only 200 POs are deducted from the ES license pool.
Controller Hardware Verification: During download, the CPU 410 firmware queries the physical SEC inserted in its front slot. If the SEC has a capacity rating of 200 POs (or 500, 1000, 1600, or 2600+), the CPU authorizes execution. If the SEC capacity is smaller than the program's PO requirement (e.g. program has 250 POs but SEC is rated for 100 POs), the CPU rejects the download or enters a non-conforming state.

Hardware Sizing Rules for Redundant S7-400H / AS 410 Pairs

For high-availability redundant architectures (AS 410-5H Redundant System), Siemens enforces strict hardware symmetry rules:

Identical SEC Capacity: Both CPU 410-5H processors in the redundant subracks must be fitted with System Expansion Cards of the exact same PO capacity. If CPU A has a 500 PO SEC, CPU B must also have a 500 PO SEC.
No Capacity Pooling Across CPUs: Hardware capacities do NOT sum. You cannot pair a 100 PO SEC with another 100 PO SEC to run a 200 PO application. In the event of a primary CPU failure or maintenance switchover, the standby CPU must be capable of executing 100% of the technological workload independently.
Online SEC Expansion: The CPU 410-5H supports online expansion of SEC capacity using the CPU 410 Expansion Pack. If a plant expands from 200 POs to 500 POs, engineers can purchase expansion entitlements via ALM and load them dynamically into both SECs in RUN mode without stopping the process.

Verification

Verify AS RT PO consumption and SEC hardware capacity through these diagnostic steps:

Check Multiproject PO Count: In SIMATIC Manager, select the AS project, right-click the Charts folder, and select Object Properties. Switch to the PCS 7 Process Objects tab. View the calculated total consumed AS RT POs (e.g., 200 POs).
Verify Hardware SEC Rating: Select the AS controller in SIMATIC Manager and open PLC -> Module Information -> Memory or open HW Config and inspect CPU 410 properties. Verify that the SEC capacity reads equal to or greater than the consumed PO count.
ALM License Utilization Audit: Launch Automation License Manager on the Engineering Station. Verify that total SIMATIC PCS 7 AS RT PO licenses show sufficient headroom and that zero license deficit warnings exist.

Limitations and Operational Precautions

When planning and purchasing AS RT PO licenses for CPU 410-5H systems, observe these commercial and technical guardrails:

Commercial Accuracy Notice: CPU 410-5H System Expansion Cards are specific hardware catalog items (e.g., 6ES7653-2CA00-0XB0 for SEC 100 PO, 6ES7653-2CB00-0XB0 for SEC 500 PO, 6ES7653-2CC00-0XB0 for SEC 1000 PO). PO upgrade packs (6ES7653-2Cx00-0XE0) are subject to Siemens commercial licensing terms. Always validate final license quantities and part numbers against current Siemens catalogs and authorized distributor quotations.
Never Mismatch Redundant SECs: Operating a redundant CPU 410 pair with mismatched SEC capacities prevents redundant coupling and synchronization (redundancy error REDF LED illuminated).
Separate OS RT PO Accounting: AS RT PO licenses authorize controller execution only. They do not license visualization on the Operator Station; WinCC OS RT PO licenses must be purchased separately for OS Servers.

Engineer FAQ

If my redundant program uses 200 POs, do I purchase 400 software licenses in ALM?

No. Software licensing in ALM accounts for the automation station as a single entity, requiring only 200 AS RT PO software licenses. However, you must purchase two physical 200 PO System Expansion Cards—one for each physical CPU module.

What happens if my program exceeds the SEC hardware capacity in CPU 410?

The CPU 410 logs a license violation in its diagnostic buffer, illuminates the EXTF LED, and will reject subsequent program downloads until an SEC upgrade pack is applied or logic POs are reduced.

Do channel driver blocks like Pcs7AnIn count toward AS RT PO consumption?

No. Channel drivers, mathematical functions, and logic blocks do not consume Process Objects. Only blocks that create OS alarms and operator controls consume POs.