1. Problem Overview
Engineers commissioning or maintaining a SIMATIC PCS 7 system frequently encounter a confusing state in the Automation License Manager (ALM): an AS Runtime license of type PO 100 is reported as "expired", "in grace period", or marked with a red X. The display does not always distinguish between three fundamentally different conditions, and an inexperienced operator can mistakenly conclude that a paid, perpetual license has been damaged when in fact the license is healthy and the CPU is consuming the bundled Process Objects (POs) as designed.
This reference documents how to interpret the ALM state for an AS Runtime PO 100 license, the difference between time-bounded (trial) and perpetual (definite) licenses, the meaning of the grace period, how the PO counter behaves when blocks are loaded, the risks of the Book-Back function, and the recovery path when a license is actually defective.
2. PCS 7 License Model Fundamentals
PCS 7 licensing is built on three orthogonal concepts that must be understood before any troubleshooting begins:
| Concept | Description | Typical Value (PO 100) |
|---|---|---|
| License Type | Definite (perpetual, purchased) vs. Time-bounded (trial/lease) | Definite |
| License Scope (PO) | Maximum number of Process Objects the CPU may own simultaneously | 100 POs |
| Validity Interval | Date range during which the license key is cryptographically accepted by ALM | Unlimited (definite) or 14/30/90 days (trial) |
| Grace Period | Tolerance window after validity expiry during which the license still functions with warnings | Typically 14 days, vendor-defined |
A Process Object (PO) in PCS 7 is the runtime representation of an automation tag, encompassing the CFC/SFC chart, the S7 chart I/Os, the OS-relevant faceplate, and the archive/messages generated from it. Adding a new CFC block of an PO-relevant type to the S7 program, compiling, and downloading causes the AS to book a PO from the license pool. Removing the block does not return the PO; only a manual Book-Back action returns unused POs to the license.
3. AS Runtime vs. OS Runtime Licenses
The field report references "AS Runtime AS (PO 100)". The catalog research provided the OS counterpart. The two are separate commercial products and must not be confused:
| Item | AS Runtime PO 100 | OS Runtime PO 100 |
|---|---|---|
| Target station | AS (S7-400 / S7-410 / AS 410 controller) | OS Server / OS Client (WinCC-based) |
| Protects | Process Objects compiled into the S7 program | Tags / faceplates / archive tags loaded into WinCC |
| Enforcement point | CPU firmware + ALM service on engineering station | WinCC RT database + ALM service on OS server |
| Counted object | CFC/SFC blocks of PO-relevant type | OS-relevant tag instances |
| Catalog example | Consult Siemens Industry Mall for current AS MLFB | 6ES7658-2XA00-0XB0 (per official Siemens product page) |
Refer to the official Siemens product entry for 6ES7658-2XA00-0XB0 PCS 7 Runtime License OS (PO 100) for the OS variant ordering details, license-key-on-USB-stick delivery form, and current pricing. The AS variant shares the same PO-counting concept and ALM workflow but uses a different article number, which must be obtained from the Siemens Industry Mall or your local Siemens representative.
4. What "Expired" Actually Means in ALM
The Automation License Manager (almserver.exe + UI almtop.exe) displays license keys in a state machine. The key states relevant to a PO 100 license are:
| Icon / Color | State | Meaning | AS Impact |
|---|---|---|---|
| Green check | Valid | Definite license, PO count within limit | None — full operation |
| Yellow triangle | Grace period active | Validity date passed; ALM still allows use for the grace interval | System logs warning; CPU remains in RUN |
| Red X | Defective / Invalid | License key corrupt, missing, or unassigned to this hardware | CPU goes to STOP on next warm restart; PO enforcement enabled |
| Gray clock | Time-bounded, expired | Trial license past its date | CPU may go to STOP after grace period |
For a definite (purchased) AS Runtime PO 100 license, an "expired" message combined with a red X almost always means one of the following:
- The license is genuinely defective (corrupted license key on the hard disk, license transferred to a different hardware fingerprint, or a re-imaged PC where the ALM license container was not migrated).
- The license was installed as a time-bounded variant (trial, rental, or upgrade voucher) and the validity interval has elapsed.
- The license is intact but PO exhaustion has caused a separate "Insufficient POs" diagnostic to surface in the AS diagnostics buffer, which an operator mis-read as "expired".
5. Reading the ALM Screens Correctly
Open the Automation License Manager on the engineering station (Start → SIMATIC → Automation License Manager → Automation License Manager). In the left-hand navigation tree, select the local PC, then click All Licenses in the right pane. Sort by License Type and inspect the row labeled AS RT PO 100 or similar:
- Column "Validity": blank → definite license. Date present → time-bounded.
-
Column "Status":
OK,In Grace Period,Expired,Defective. -
Column "PO Used / PO Total": e.g.
37 / 100indicates that 37 POs are currently booked by the loaded S7 program. - Column "Target System": should match the AS hardware serial number (MLFB + serial).
To confirm whether the PO 100 license is the actual cause of a CPU STOP, read the AS diagnostics buffer via SIMATIC Manager → PLC → Diagnostics/Setting → Diagnostics Buffer. Entries of type PO limit exceeded (event ID depends on PCS 7 version) confirm PO exhaustion. Entries of type License check failed indicate a defective or missing ALM key.
6. The Book-Back Procedure (And Why It Is Risky)
Book-Back returns Process Objects to the license pool so they can be re-used on the same or a different AS. The procedure in ALM:
- Open Automation License Manager on the engineering station that owns the license.
- Right-click the
AS RT PO 100license entry. - Select Book-Back / Return License.
- Confirm the target AS (identified by its hardware serial / PLC ID).
- Wait for ALM to contact the AS and reset the PO counter.
Book-Back is typically required only when:
- An AS is being decommissioned and the PO 100 license must move to a replacement controller.
- The PO counter has been over-booked by archived programs and the operator needs to free capacity without reordering.
- Siemens support requests a license reset for diagnostic purposes.
7. Recovery From a Genuinely Defective License
When ALM shows a red X and Siemens support confirms the key is corrupted (typical after a non-Siemens disk clone, BIOS UUID change, or accidental deletion of the AX SFS folder), follow this recovery sequence:
- Open a support request on the Siemens Industry Online Support portal, quoting the AS hardware serial number, the license MLFB, and the License Key ID shown in ALM (column License Key).
- Request a CoL (Certificate of License) reissue or a replacement license key, depending on the underlying cause.
- If the original USB License Key stick is intact, re-import the key on the engineering station; ALM will rebuild the
AX NF ZZcontainer automatically. - Transfer the recovered license back to the AS via the standard ALM "Assign License" workflow (drag-and-drop or right-click → Assign).
- Perform a CPU warm restart, monitor the diagnostics buffer for a clean startup, and verify the PO counter in ALM.
For a temporary workaround while waiting for a replacement, an older license key from the same PO family (e.g. PO 250 or PO 500) can be assigned in its place to bring the AS back to RUN; the PO limit is simply the lower of the two license values during the overlap period.
8. Catalog Numbers and Ordering Reference
Always confirm the current article number in the Siemens Industry Mall before ordering, as PCS 7 license MLFBs are version-keyed (V8.x vs. V9.x vs. V9.1). The article provided in the source research is:
- 6ES7658-2XA00-0XB0 — SIMATIC PCS 7, Runtime License OS (PO 100), single license for 1 installation, R-SW, license key on USB stick. View product entry.
The AS Runtime PO 100 counterpart is ordered under the same 6ES7658 family with a different suffix; the exact article number must be obtained from the Siemens Industry Mall by filtering on SIMATIC PCS 7 → Licenses → AS Runtime. When upgrading from V8.x to V9.x, an upgrade license (different MLFB) is required — a V8.x AS Runtime PO 100 is not valid on a V9.x system.
9. Extending or Replacing the PO 100 License
Three options exist when the PO 100 ceiling becomes insufficient:
| Option | Action | Impact on Runtime |
|---|---|---|
| Order larger PO bundle (PO 250 / PO 500 / PO 1000) | Purchase higher-tier AS Runtime license; assign in ALM | None — CPU continues to RUN during the assignment if both licenses co-exist |
| Power Pack (upgrade) | Order the Power Pack article for the PO increment needed | None — Siemens-issued upgrade reuses the existing key |
| Reduce PO count in S7 program | Remove unused CFC blocks, consolidate by means of multi-instance blocks | Requires download; possible brief AS restart if PO was already booked |
10. Verification Checklist After Any License Action
- Open ALM, locate the AS Runtime PO 100 entry, confirm status is
OK(green check). - Confirm PO Used / PO Total matches the number of PO-relevant blocks in the loaded S7 program (PCS 7 reports this in the CFC editor under Options → PO Count).
- Read the AS diagnostics buffer; no entries of type
LicenseorPO limitshould remain. - Trigger a faceplate read on the OS; the value must update and not raise a "license missing" popup.
- Export the ALM report to a file for audit (right-click → Export → XML or CSV) and store it with the project documentation.
11. Troubleshooting Matrix
| Symptom | ALM Display | Probable Cause | Corrective Action |
|---|---|---|---|
| AS goes to STOP, SF LED on, diagnostic buffer shows "PO limit exceeded" | PO Used = PO Total (e.g. 100/100) | PO exhaustion | Remove blocks, order larger PO bundle, or perform Book-Back after backup |
| AS goes to STOP immediately after re-imaging engineering PC | Red X on AS Runtime PO 100 | License not migrated with disk image | Re-import license from USB stick; re-assign to AS |
| CPU in RUN, ALM shows "In Grace Period" | Yellow triangle | Time-bounded (trial) license nearing expiry | Order replacement definite license before grace period elapses |
| PO Used counter higher than the S7 program seems to justify | OK, but PO count inflated | Archived CFC charts still booked from old download | Compile S7 program with "Book POs only for active charts" option, then Book-Back to reset counter |
| License key visible in ALM but AS reports "License not found" | OK on engineering PC | License not assigned / assigned to wrong AS | Drag the key onto the correct AS node in ALM navigation |
| After BIOS or hard disk change, ALM shows red X | Red X | License tied to host fingerprint | Use ALM "Reactivate" (if within repair window) or request CoL reissue from Siemens |
12. FAQ
Does a PCS 7 AS Runtime PO 100 license actually expire?
No. A definite (purchased) PCS 7 AS Runtime PO 100 license has no expiry date and does not expire. Only time-bounded variants — trial licenses, rentals, and upgrade vouchers — carry a validity date. If ALM shows an expiry date on your key, verify in the ALM detail view that the key type is "definite"; if it is, contact Siemens support because the key file is either corrupted or has been mis-issued.
What is the difference between an "expired" and a "defective" PCS 7 license?
"Expired" in ALM means the validity date on a time-bounded key has passed; the key was once valid but is no longer cryptographically accepted after the grace period. "Defective" (red X) means the key file is unreadable, the host fingerprint has changed, or the key has been assigned to a different target. A defective definite license can usually be reactivated by Siemens support; a definitively expired trial license cannot.
What happens during the AS Runtime Book-Back procedure?
Book-Back returns all POs currently booked to a specific AS back to the license pool, so they can be re-used on the same or a different controller. The trade-off is severe: the entire S7 user program on the target AS is erased, the CPU is forced into STOP, and all retentive data on that AS is lost. Always take a full S7 project backup before performing Book-Back, and never run Book-Back on a production AS without a scheduled outage.
How can I check how many POs my PCS 7 project is currently using?
Open SIMATIC Manager, load the S7 program to the engineering station, then in the CFC editor choose Options → PO Count. The dialog reports the number of PO-relevant blocks in the offline program. Compare this number to the PO Used / PO Total column of the AS Runtime entry in the Automation License Manager. The two values should match within a small margin; large discrepancies usually indicate that archived charts are still occupying PO slots.
Can I extend a PCS 7 AS Runtime PO 100 license without buying a full new license?
Yes, via the Siemens Power Pack mechanism. A Power Pack is an upgrade license that reuses the existing license key and adds the missing POs (for example, from PO 100 to PO 250). The Power Pack is assigned in ALM in the same way as a full license and does not interrupt AS runtime. Alternatively, a separate larger PO bundle (PO 250, PO 500, PO 1000) can be ordered and assigned alongside the existing PO 100; the system uses the larger of the two for enforcement.