Diagnosing AS RT Process Object License Deficits and Recovering Booked POs in PCS 7

When downloading to a SIMATIC S7-400 or CPU 410-5H controller and Step 7 flags an AS RT Process Object (PO) deficit despite having sufficient total licenses installed in Automation License Manager (ALM), the error indicates that available PO licenses are booked to other projects or older versions on the Engineering Station. PCS 7 enforces two separate licensing mechanisms: physical CPU capacity on the System Expansion Card (SEC) and countable AS RT PO software licenses in ALM. When a CPU is overwritten with a new project without first releasing the previous project's POs, those licenses remain deducted in the ES database. To recover booked POs, open the original project, navigate to the Chart folder Properties > Charts tab, and execute 'Transfer back Process Objects'. Alternatively, purchase additive AS RT PO packages to cover the deficit.

Executive Summary

In SIMATIC PCS 7 architectures, Process Object (PO) management governs both the physical scaling of the controller hardware and the legal software runtime entitlement of the engineering system. Engineers expanding existing programs or commissioning multi-project environments frequently encounter unexpected license warning popups during S7 downloads stating that required AS RT POs exceed available quantities (e.g., 738 POs required, but only 728 available), even though ALM reports an aggregate total of 1,300 POs on the engineering drive. This guide resolves the confusion between CPU 410 SEC hardware capacity and countable AS RT PO software licenses, explains how complete downloads across multiple projects tie up PO balances, and provides the step-by-step procedure to book back or additively expand Process Objects.

Architecture and Fundamental Mechanics

The Dual Licensing Architecture of PCS 7 Process Objects

+-------------------------------------------------------------------------+
|                    SIMATIC PCS 7 AS PROCESS OBJECT LAYERS               |
+-------------------------------------------------------------------------+
                                    |
         +--------------------------+--------------------------+
         |                                                     |
         v                                                     v
+------------------------------------+           +------------------------+
| LAYER 1: Hardware Scaling (SEC)    |           | LAYER 2: Software RT PO|
| Physical Controller Limit          |           | Countable ALM Licenses |
|                                    |           |                        |
| - Stored in CPU 410-5H SEC Token   |           | - Installed on ES Host |
| - Example: 1,600 AS PO Limit       |           | - Example: 1,300 Total |
| - Governs max loadable POs in CPU  |           | - Booked per project   |
+------------------------------------+           +------------------------+
                                                             |
                                                             v
+-------------------------------------------------------------------------+
|                   Engineering Station Local PO Registry                 |
|                                                                         |
|   Total Installed Licenses in ALM:           1,300 PO                   |
|   - Previously Booked to Old Project 1:        572 PO  <-- [STRANDED]   |
|   - Currently Remaining Available Balance:     728 PO                   |
|   - Required for Current Project 2:            738 PO                   |
|   -------------------------------------------------------------------   |
|   RESULT: DEFICIT OF -10 PO -> S7 Download Pop-Up Warning Triggered!    |
+-------------------------------------------------------------------------+

How POs Become Stranded

Project Overwrite Without 'Book Back': When an engineer loads a new project (Project 2) into a CPU that previously ran Project 1, the ES registers that Project 1's booked POs (e.g., 572 POs) are still active on that controller. Unless the engineer opens Project 1 and explicitly releases them back to ALM via the Transfer back Process Objects utility, those 572 POs remain permanently reserved on the ES.
Counting Methodology: An AS RT PO is counted for every CFC block that has Operator Control and Monitoring (OCM) enabled (e.g., MotL, VlvL, PIDConL, OpDi01) or generates alarms, as well as SFC charts and BATCH instances.
Additive Sizing: Additive AS RT PO licenses are available in standard packages of 100, 1,000, and 10,000 POs. For licensing validation and package ordering, always consult an authorized Siemens distributor or the Siemens Industry Mall.

Step-by-Step Implementation Procedure

Step 1: Inspect Current PO Booking Status in SIMATIC Manager

In SIMATIC Manager, select the Chart folder of the active project.
Right-click the Charts folder and select Object Properties.
In the Properties dialog, select the Charts tab.
Review the licensing summary:
- Configured Process Objects: Displays the PO count in the current project (e.g., 738).
- Booked Process Objects: Displays POs currently credited from ALM.
- Available Process Objects: Displays remaining unbooked licenses in the local ALM pool.

Step 2: Recover Stranded POs from Previous Projects (Book Back Procedure)

If a previous project was overwritten on the CPU and its POs remain booked:
In SIMATIC Manager, open the original project (Project 1) from archive or disk.
Select the Charts folder, right-click, and open Object Properties > Charts.
Click the button Transfer back Process Objects... (or Prozessobjekte zurückbuchen).
Confirm the warning dialog: Note that releasing POs marks Project 1 as uncommissioned and clears its reservation in the ES database.
Verify that the recovered PO balance immediately returns to the available ALM license pool.

Step 3: Additive License Installation via ALM (If True PO Deficit Exists)

If the plant has legitimately expanded beyond the total licensed capacity (e.g., needing 1,500 POs on a 1,300 PO license):
Procure an additive SIMATIC PCS 7 AS Runtime License (100 POs, 1,000 POs, or 10,000 POs).
Note: Confirm the exact order number (MLFB) corresponding to your PCS 7 version with an authorized Siemens distributor or the Siemens Industry Mall.
Open Automation License Manager (ALM) and transfer the newly purchased license key to the ES hard disk.
In ALM, right-click the transferred license and select Check License Key to ensure valid status.

Step 4: Book Process Objects to Current Project and Download

Return to the active project in SIMATIC Manager.
Open the Charts folder properties > Charts tab.
Verify that the Available Process Objects field now exceeds the Configured Process Objects.
Initiate the AS program download: Target system > Download to target system > Changes Only.
The download proceeds cleanly without license warning popups.

Verification

Download Execution: Confirm that the AS download executes to completion without displaying the license shortage warning.
Chart Folder Property Audit: Re-open the Chart folder properties and verify that configured POs match booked POs exactly, with remaining available balance reported accurately.
Diagnostic Buffer Check: Inspect the CPU Module Information (Ctrl+D) to ensure no licensing discrepancy events are recorded.

Limitations and Operational Precautions

Lost Project Files: If the original project that booked the POs was permanently deleted or lost without a backup, the booked POs cannot be released via standard menus and may require Siemens Technical Support intervention.
Hardware SEC Ceiling: Adding software AS RT PO licenses in ALM cannot exceed the physical capacity limit of the System Expansion Card (SEC) inside the CPU 410-5H. If the CPU hardware limit is reached, an SEC Expansion Pack must be loaded directly onto the physical SEC card.

Engineer FAQ

What is the difference between AS PO and AS RT PO?

AS PO represents the physical CPU capacity scaled on the System Expansion Card (SEC); AS RT PO represents the countable software licenses in ALM on the Engineering Station.

Why did downloading a new project cause a license shortage?

The old project's booked POs were not transferred back to ALM, leaving them deducted in the ES database and starving the new project.

How do I return booked POs to the license pool?

Open the old project in SIMATIC Manager, go to Chart folder Properties > Charts tab, and click 'Transfer back Process Objects'.

Does transferring back POs stop the running CPU?

Yes, transferring back POs strips the CPU of its licensed program status, which requires an AS STOP if connected online.

What block types consume an AS RT PO?

Blocks with Operator Control and Monitoring (OCM) enabled—such as MotL, VlvL, PIDConL, OpDi01, SFC charts, and dosing blocks—each consume 1 PO.

Do module driver blocks consume POs?

Standard module driver blocks (Pcs7AnIn, Pcs7DiIn) connected to control blocks do not consume additional POs if integrated into standard APL control loops.

Can I buy 10 PO expansion licenses?

No. Siemens provides AS RT PO expansion licenses in increments of 100, 1,000, and 10,000 POs.

Where can I see total available POs in ALM?

In Automation License Manager, look for the license family 'SIMATIC PCS 7 AS RT PO' installed on the local drive.

Can multiple engineering stations share an AS RT PO license pool?

Yes, if ALM network floating license servers are configured across the engineering network.

What happens if I ignore the download license warning?

The CPU allows program download and runs, but the system logs a licensing violation, which creates legal non-compliance and risks support invalidation.