System Behavior and Hardware Restrictions When Exceeding AS Process Object Limits in PCS 7

When a SIMATIC PCS 7 engineering program exceeds the licensed Process Object (PO) limit, system behavior depends strictly on whether the bottleneck is the physical CPU 410-5H System Expansion Card (SEC) or the software AS RT PO license in Automation License Manager (ALM). If the CFC program PO count exceeds the hardware SEC capacity, the CPU 410-5H operating system hard-blocks compilation and download, preventing changes from being loaded into the controller while keeping the running AS in RUN mode. In contrast, exceeding the software AS RT PO license in ALM displays a warning during download and logs a deficit, but does not stop the CPU or prevent loading.

Executive Summary

Process Object (PO) licensing in SIMATIC PCS 7 is governed by two distinct mechanisms: hardware-enforced CPU capacity on the CPU 410-5H System Expansion Card (SEC), and software runtime licensing managed via Automation License Manager (ALM). During plant expansions, adding technological blocks (such as motors, valves, or analog monitors) generates additional Process Objects. When the total PO count exceeds licensed boundaries, plant engineers frequently worry whether the running controller will shut down or trip production. This guide explains the precise runtime boundaries of PO overrun, contrasts SEC hardware locks with ALM software licensing, details SEC expansion procedures, and outlines commercial guardrails.

Architectural and System Mechanics

Dual-Tier Process Object Architecture in SIMATIC PCS 7:

CPU 410-5H System Expansion Card (SEC) Hardware Licensing:
- Physical Capacity Lock: The CPU 410-5H requires an SEC card plugged into the rear of the CPU. The SEC determines the maximum allowable PO capacity (e.g., 100, 500, 1000, 1600, or 2000+ POs).
- Hardware Enforcement: The CPU firmware verifies the CFC PO count before allowing a program download. If the program PO count exceeds the SEC card capacity, CFC download is strictly prohibited (Download not possible: Process Object limit of CPU exceeded). The CPU remains in RUN with the existing program, but delta or full downloads are rejected.
- Upgrade Mechanism: Upgrading SEC capacity requires procuring an SEC Expansion Pack (e.g., 100 PO 6ES7653-2CA00-0XE0 or 500 PO 6ES7653-2CC00-0XK0), uploading the CPU request file via the Siemens License Portal, and applying the resulting release file via ALM.
AS RT PO Software Licensing (ALM on Engineering Station):
- Software Accounting: Software PO licenses (AS RT PO) reside in ALM on the Engineering Station.
- Runtime Consequence: If the PO count exceeds installed software licenses, the ES displays a license deficit warning during download, and ALM records a deficit. The download is permitted, and the AS does not stop.
- Redundancy Rule: For redundant AS pairs (e.g., dual CPU 410-5H), software AS RT PO licenses are required only once for the redundant pair, whereas both physical CPUs must possess matching SEC hardware cards.

Step-by-Step Engineering and Implementation Procedure

Step 1: Audit Current Process Object Consumption in CFC

Open any CFC chart in SIMATIC Manager.
Select 'Utilities' -> 'Process Objects' -> 'Display...'.
The dialog displays the total POs configured in the project, broken down by chart and block type, compared against the licensed limit.

Step 2: Differentiate Hardware SEC Capacity from Software ALM POs

In SIMATIC Manager, select the CPU 410-5H, open 'PLC' -> 'Diagnostic/Setting' -> 'Module Information'.
Select the 'Performance Characteristics' tab; inspect the 'SEC Capacity' (e.g., 500 PO).
Open Automation License Manager (ALM) on the ES; check the quantity of SIMATIC PCS 7 AS RT PO licenses installed on drive C:.

Step 3: Handle Hardware SEC Limit Overrun

If your program requires 628 POs and the SEC card is rated for only 500 POs:
1. You cannot download changes until the SEC is expanded.
2. Procure the required expansion pack (e.g., two 100 PO packs or one 500 PO pack) from your authorized Siemens distributor.
3. Generate the activation request from ALM, submit it to the Siemens Industry Online Support (SIOS) License Portal, and retrieve the activation key file.
4. Transfer the activation key to the SEC card via ALM while connected to the CPU.

[!NOTE]
SEC online activation can take up to 24 hours depending on distributor order processing; plan expansion purchases in advance of commissioning deadlines.

Step 4: Handle Software AS RT PO Shortage

If the SEC has sufficient capacity (e.g., 1000 PO) but ALM lacks software AS RT POs:
1. Download can proceed; acknowledge the warning dialog.
2. Procure matching AS RT PO volume packages to restore license compliance.

Verification

To verify PO capacity and license alignment:
1. In Module Information -> Performance Characteristics, confirm that the SEC PO capacity reflects the expanded value.
2. In CFC, execute 'Utilities' -> 'Process Objects' -> 'Display...'; verify that PO utilization is within 100% of SEC capacity.
3. Execute a Delta Download to the CPU; confirm that the download completes successfully without error messages.
4. Check ALM to confirm zero license deficit alerts.

Limitations and Operational Precautions

Operational precautions:
- A CPU 410-5H will never stop running existing automation logic solely because an engineering download exceeds PO limits; the download is rejected beforehand.
- Never treat estimated I/O-to-PO ratios as actual license counts; always use the CFC 'Process Objects' calculation tool.
- Booking back Process Objects from a CPU 410-5H requires placing the CPU in STOP mode; do not attempt SEC PO recovery on a running production controller.

Engineer FAQ

Q: Will the CPU stop if I exceed the AS PO license limit?

A: No. If the hardware SEC limit is exceeded, CFC rejects the download entirely, leaving the CPU running its previous program. If the software ALM license is exceeded, a warning is displayed, but the download proceeds without stopping the CPU.

Q: What is the difference between SEC capacity and AS RT PO licenses?

A: SEC capacity is a physical hardware limit embedded in the CPU 410-5H expansion card. AS RT PO licenses are software entitlements installed in ALM on the Engineering Station.

Q: How many PO licenses does a redundant AS pair need?

A: Redundant AS pairs require matching physical SEC cards for each CPU, but only one pool of software AS RT PO licenses.

Q: How long does an SEC upgrade take to process?

A: License portal key generation is automated once order numbers are delivered, but procurement and commercial verification typically take 24 to 48 hours.

Q: Can I reduce PO count by deleting unused CFC charts?

A: Yes. Deleting technological blocks (such as MotL or VlvL) and running 'Process Objects Display' recalculates and frees up consumed POs.

Technical References

Related Tags

Process Objects, CPU 410-5H, System Expansion Card, AS RT PO, PCS 7 Licensing

Process Objects

CPU 410-5H

System Expansion Card

AS RT PO

PCS 7 Licensing

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System Behavior and Hardware Restrictions When Exceeding AS Process Object Limits in PCS 7