Managing AS Process Object Licensing and CPU PO Limits in SIMATIC PCS 7

Managing Process Object (PO) licensing in SIMATIC PCS 7 with S7-410 controllers requires distinguishing between two separate mechanisms: the CPU hardware PO limit governed by the System Expansion Card (SEC) and the software runtime PO licenses managed by Automation License Manager (ALM). Exceeding the hardware SEC PO limit strictly blocks program downloads to the CPU, whereas software runtime PO deficits result in licensing compliance warnings in the engineering system and WinCC OS.

Differentiating CPU Hardware PO Limits from ALM Runtime Licenses

In SIMATIC PCS 7 (specifically with the CPU 410-5H Process Automation controller and PCS 7 V8.x/V9.x/V10), process object accounting operates across two separate tiers:

1. CPU Hardware Limit (System Expansion Card - SEC)

The CPU 410-5H hardware capacity is defined by the physical System Expansion Card (SEC) plugged into the back of the CPU.
SEC variants range from 100 POs up to 2600 POs (or Unlimited / 2800+ for specific firmware versions).
This is a hard technical boundary enforced by the CPU firmware. If the total number of process objects compiled in the CFC chart folder exceeds the SEC limit, the engineering system blocks the download to the CPU.
The SEC capacity can be expanded online without replacing hardware using the CPU 410 PO upgrade mechanism.

2. Software Runtime License (AS RT PO in ALM)

Software licenses are managed by Siemens Automation License Manager (ALM) installed on the Engineering Station (ES).
The license key is designated as SIMATIC PCS 7 AS Runtime Process Objects (100 / 1000).
When the project is compiled, the PCS 7 Engineering System checks ALM:
Booked / Used: The number of process objects currently utilized across all automation stations in the project.
Available: The total pool of AS RT PO license keys installed on the local or network license server.
Currently Still Available: The floating margin remaining before license exhaustion.
If software PO licenses are exhausted, PCS 7 allows engineering to proceed but logs licensing compliance warnings and displays periodic non-compliance popups in SIMATIC Manager and WinCC.

Monitoring and Calculating AS RT PO Consumption in Automation License Manager

To inspect and reconcile process object consumption across controllers and engineering stations:

Step 1: Check Process Object Count in SIMATIC Manager

In SIMATIC Manager, select the Chart folder of the target S7 Program.
Select Options -> Charts -> Process Objects....
The Process Objects dialog displays:
- Configured Process Objects: Total POs used by blocks in this specific chart folder.
- Loaded Process Objects: POs currently loaded into the online controller.
- CPU Limit: Maximum PO capacity permitted by the CPU's System Expansion Card (SEC).

Step 2: Inspect Multiproject PO Licensing Summary

Select the top-level Multiproject or Project icon in SIMATIC Manager.
Select Options -> PCS 7 License Information....
In the license dialog, review the tabulated categories:
- AS RT PO: Total configured across all AS stations vs. total licenses found in ALM.
- OS RT PO: Total WinCC archive and process tags vs. installed OS runtime licenses.
Verify the column Currently still available:
- If positive: Sufficient floating licenses exist.
- If negative: Additional AS RT PO license packages (e.g., 100 or 500 PO packages) must be transferred via ALM.

Step 3: Manage License Keys in Automation License Manager

Launch Automation License Manager from the Windows Start menu.
Select the target drive housing the license keys (e.g., C: or central network license server).
Filter by license family SIMATIC PCS 7.
Ensure the license key PCS 7 AS Runtime License displays status Valid and that the total quantity covers the total booked count reported in SIMATIC Manager.

Verification

In CFC, initiate a test download (CPU -> Download -> Changes Only). Confirm that configured process objects do not exceed the CPU limit.
In SIMATIC Manager, confirm that Options -> PCS 7 License Information displays no red or negative values for AS RT PO.
Inspect the CPU 410 diagnostic buffer (Ctrl+D in SIMATIC Manager) and confirm zero Process object limit exceeded entries.

Limitations and Operational Precautions

Exceeding ALM software licenses does not stop a running plant, but exceeding the SEC hardware PO limit prevents downloading essential engineering changes or new logic to the controller.
CPU 410 SEC expansion can be executed online while the plant is operating, but requires an SEC PO upgrade card and activation via the CPU 410 Upgrade Service in ALM.
Not every CFC block consumes a Process Object; standard arithmetic and basic connectors do not consume POs. Process Objects are consumed by control blocks with operator control and monitoring (OCM) attributes, motor/valve actuators, PID controllers, and message-generating blocks.

Engineer FAQ

What happens if I exceed the SEC PO limit during a plant turnaround?
If the compiled project exceeds the physical SEC limit, SIMATIC Manager will abort the download with an error message indicating insufficient CPU process objects. Logic changes cannot be downloaded until you either reduce the number of PO blocks or perform an online SEC expansion.
How do I reduce Process Object consumption without deleting field equipment?
Combine auxiliary logic, eliminate unused motor/valve driver blocks, disable the OCM possible attribute on internal intermediate calculation blocks, or convert individual message-generating blocks into aggregated diagnostic indicators.
Can AS RT PO licenses be shared across multiple engineering stations?
Yes. Automation License Manager can be configured as a central network license server. Multiple engineering stations pointing to the server can float AS RT PO licenses from a shared pool.
Does an S7-410H redundant pair require double the SEC POs?
Each CPU 410 in a redundant S7-410H pair must have its own physical System Expansion Card of identical capacity. However, for software runtime licensing in ALM, a redundant station consumes only a single set of AS RT POs corresponding to the configured program.
Why does PCS 7 report negative available POs even though downloads work?
This indicates that the program complies with the physical CPU SEC limit (allowing downloads to succeed), but the engineering system detects that the total project PO count exceeds the software license keys registered in ALM.

Technical References

Siemens Industry Online Support Entry ID 74509647: Process Object Licensing in SIMATIC PCS 7.
Siemens Manual: Process Control System PCS 7 - Licenses and Configuration Limits.
Siemens Industry Support: CPU 410-5H Process Automation System Expansion Card (SEC) Upgrade Guide.