Problem Statement
During the first online download from TIA Portal (V15.1 through V19) to a SIMATIC S7-1500 CPU 1517F-3 PN/DP (article number 6ES7517-3FP00-0AB0, or the -0AK0/-0AK1/-0AK2 firmware-revision successors), the load operation terminates with the status "Loading is aborted" and the CPU refuses to transition from STOP into RUN. The online diagnostics dialog reports:
- Module status: Module exists + Faulty
- LED: SF (red, group fault) illuminated
- Diagnostic event: CPU info: Follow-on operator mode change
- Configured power-on behavior: no startup
- Pending startup inhibit #1: Memory card missing, wrong type, wrong content or protected
- Pending startup inhibit #2: HW configuration not loaded/change or not successfully finished
Because the S7-1500 family stores the project runtime, hardware configuration, and (for fail-safe CPUs) the safety signature on the SIMATIC Memory Card rather than in onboard flash, an empty card slot combined with no previously loaded hardware configuration yields an unrecoverable startup condition until both inputs are supplied. The error is not firmware-bug-specific, but it presents almost universally on first commissioning because both preconditions are unmet on a fresh machine.
Affected Components and Compatible Revisions
| Component | Article number | Relevant detail |
|---|---|---|
| CPU 1517F-3 PN/DP | 6ES7517-3FP00-0AB0 | Work memory 3 MB code / 10 MB data; bit execution time 2 ns |
| CPU 1517F-3 PN/DP (FW V2.9) | 6ES7517-3FP02-0AB0 | Firmware V2.9, TIA Portal V17 required |
| CPU 1517F-3 PN/DP (FW V3.0) | 6ES7517-3FP03-0AB0 | Firmware V3.0/V3.1, TIA Portal V18/V19 required |
| SIMATIC Memory Card 4 MB | 6ES7954-8LE03-0AA0 | Minimum size for S7-1500; sufficient for code-only CPU 1517 |
| SIMATIC Memory Card 12 MB | 6ES7954-8LF03-0AA0 | Recommended for typical F-program + Web server + traces |
| SIMATIC Memory Card 24 MB | 6ES7954-8LG03-0AA0 | Recommended for full safety + recipes + OPC UA server |
| SIMATIC Memory Card 256 MB | 6ES7954-8LL03-0AA0 | For extensive logging, web-server HTML, large STEP 7 Safety libraries |
| SIMATIC Memory Card 2 GB | 6ES7954-8LP02-0AA0 | Maximum; required only for very large Web-Server datasets |
Verify the memory card revision letter matches your TIA Portal release. Cards older than HW revision 03 (the suffix -0AA0 variant in the table) cannot be read by firmware V3.x CPUs and will themselves generate the "wrong content" inhibit.
Decoding the Diagnostic Buffer
The S7-1500 maintains a battery-backed diagnostic buffer; the entries appear in reverse chronological order. Translate each line of the user-visible status to the underlying cause as follows:
| Visible status | Technical meaning | Direct action |
|---|---|---|
| Module exists / Faulty | Hardware detected on the rack but the CPU cannot complete startup diagnostics because required project data is missing | Open Online > Online & Diagnostics and read the diagnostic buffer, not just the online view |
| SF (red) | Group fault: at least one pending inhibit or a hardware mismatch is preventing RUN | Check RUN, STOP, ERROR, MAINT combination per the S7-1500 LED table below |
| Follow-on operator mode change | CPU transitioned into STOP as a result of a previous mode change (informational; not the root cause) | Ignore if other entries point at missing card or missing HW config |
| Power-on mode set: no startup | The CPU was configured for "No startup" or last download set Power-On to STOP | Either change Power-On mode in Device Properties > Startup to Warm restart RUN or perform MRES |
| Memory card missing, wrong type, wrong content or protected | Card slot empty, card formatted in a different CPU, card password-protected, or card HW revision mismatched | Insert a compatible, unlocked, project-formatted card |
| HW configuration not loaded/changed or not successfully finished | Project on the PG/PC has a hardware topology that was never downloaded, or a previous download was interrupted before completion | Re-download hardware configuration (target system > "Download to device > Hardware configuration") |
Root Cause Matrix
Map symptom combinations to root cause; this matrix is the fastest triage path on the shop floor:
| SF | MAINT | RUN | STOP | Card slot | Diagnostic message present? | Most likely root cause |
|---|---|---|---|---|---|---|
| On | Off | Off | On | Empty | Memory card inhibit | Insert compatible SIMATIC Memory Card |
| On | On | Off | On | Card present | Memory card wrong content/protected | Reformat or replace card; check write-protect slider |
| On | Off | Off | On | Card present | HW configuration inhibit only | Download HW configuration first, then software |
| On | Off | Off | On | Card present | Both inhibits | Card contains foreign project; reset card or load a complete project including HW config |
| Off | On | Off | On | Card present | No startup, no inhibit | Configured Power-On mode is STOP; perform MRES or change parameter |
| On | Off | Off | Blink | Card present | F-signature mismatch | Safety program mismatch; recompile F-program with F-CPU password |
Resolution Step 1 — Install a Compatible SIMATIC Memory Card
- Power off the CPU. The S7-1500 card slot is hot-swappable on most firmware revisions but the safest practice is to remove power before the first-ever insertion.
- Inspect the card packaging for the article number. Anything other than a 6ES7954-8xx03-0AA0 (or newer -0AB0) is suspect; non-Siemens SD cards formatted to look like SIMATIC cards will be rejected with inhibit message #1.
- Verify the write-protect slider on the card is in the unlocked position. The slider is a small plastic tab on the long edge of the SD card housing; "lock" leaves the padcontacts recessed.
- Insert the card with the label facing the front of the CPU. The slot is keyed; do not force. The card should click into its spring-loaded ejector.
- Power the CPU. The MAINT LED will flash briefly while the CPU detects the card; if the card is blank, the SF LED will remain on because the project is empty.
Resolution Step 2 — Transfer the Hardware Configuration
- In TIA Portal, open the project tree, right-click the CPU 1517F-3 PN/DP device icon, and select Download to device > Hardware configuration.
Equivalent menu path: Online > Download to device > Hardware and software (only changes). - In the Extended download dialog confirm:
- Interface: PN/IE
- Connection: Subnet > PN/IE_1
- Target device IP: must match the IP physically configured on the CPU's PROFINET port (next section)
- Click Search. TIA Portal will broadcast a DCP (Discovery and Configuration Protocol) probe on the configured interface. The CPU should appear with its MAC address and current IP. If the CPU does not appear, see the network section below.
- Select the CPU and click Download. The dialog will warn that safety programs require the F-password; enter it when prompted.
- When the dialog offers "Download hardware configuration including safety program", accept it.
- Wait for the dialog "Downloading completed successfully". The CPU will perform an internal restart and the RUN LED should turn green.
Resolution Step 3 — Confirm the PG/PC Subnet Alignment
The user question — "the IPv4 IP address and network mask of the machine and the CPU must be the same?" — reflects a common first-commissioning confusion. The strict rule is identical subnet, distinct host address. Two devices with the same IP address will not communicate at all; two devices in different subnets separated by a router will require explicit routing configuration that TIA Portal's default download does not establish.
| Parameter | CPU 1517F (PROFINET port X1) | PG/PC | Required relationship |
|---|---|---|---|
| IPv4 address | e.g., 192.168.0.1 | e.g., 192.168.0.10 | Different hosts, same /24 |
| Subnet mask | 255.255.255.0 | 255.255.255.0 | Identical |
| Default gateway | Empty (or router if plant-wide access needed) | Same as CPU if both must reach a plant router | Same gateway only if both traverse the same router |
| VLAN ID | Untagged by default | Untagged | Must match switch port PVID |
Three on-CPU configuration paths exist for the IP:
- DCP via TIA Portal: Online > Accessible nodes, right-click the discovered CPU, Assign IP address. Use this path when the CPU has no IP (factory state, link-local 0.0.0.0).
- CPU display: Settings > Addresses > X1 IP on the integrated display. Useful when the PG/PC cannot ping because of subnet mismatch.
- SIMATIC Memory Card: pre-populate via the card's S7-job, then insert. Used for batch commissioning.
ping <cpu-ip>. A successful response confirms layer-3 reachability before the next download attempt. If Request timed out persists, the subnet mismatch or a managed switch port blocking DCP multicast (LLDP frames on MAC 01:80:C2:00:00:0E) is the more likely culprit.STEP 7 Safety Mode Handling for the F-CPU
The 1517F variant requires two passes: a standard project download and a safety-program download. The safety download is gated by the F-password; without it, TIA Portal will surface "Download aborted" at the very last step even if the standard program completed successfully.
- Open Safety Administration editor in TIA Portal. Confirm the F-runtime group is generated and the F-signature version is > 0.
- Right-click the F-runtime group → Compile. Resolve any compilation errors before attempting the download.
- Right-click the CPU → Download to device > Software (only changes). Enter the F-password when prompted.
- TIA Portal will issue a "Passivation of the F-runtime group" dialog. Confirm. The F-IO will go to safe state for the duration of the download (typically 5–25 seconds).
- After completion the F-runtime group is restarted automatically and the F-signature is written to the card header.
TIA Portal Online and Download Sequence (Reference)
The sequence below is the canonical first-commissioning flow for a 1517F; each step must complete without error before the next is started.
- PG/PC interface assignment: Options > Set PG/PC interface > S7ONLINE (STEP 7) → <Intel/Realtek PROFINET>.
- Accessible nodes: Online > Accessible nodes. The CPU appears with MAC and current IP.
- Assign IP (if needed): right-click CPU → Assign IP address. Use the same /24 as the PG/PC.
- Online & Diagnostics > Memory > Format: only if the card is suspected to be non-blank. Skip if the card is new.
- Compile HW: device → Compile > Hardware (rebuild all).
- Download HW config first: Online > Download to device > Hardware and software (only changes). Watch the RUN LED transition to green.
- Download software: same menu, second pass if HW was downloaded separately.
- Download safety program: with F-password.
- Go online: Online > Go online. Verify the watch table, force table, and trace behave as expected.
LED Pattern and Status Mapping
The 1517F-3 PN/DP front-panel LED layout and the meanings relevant to this error class are summarised below.
| LED | Color | Steady state during this fault | Meaning |
|---|---|---|---|
| RUN | Green | Off | CPU is in STOP and cannot transition to RUN because of an inhibit |
| ERROR (SF) | Red | On | At least one group-fault condition (missing card or missing HW config) |
| MAINT | Yellow | Off or flashing | Off = card absent; 2 Hz flash = card present but content mismatch |
| STOP | Yellow | On | CPU is held in STOP |
| LINK X1 / X2 | Green | On (PG/PC connected) | Physical link present at PROFINET port X1 / X2 |
| RX/TX X1 / X2 | Yellow | Flashes on traffic | Active data exchange on the PROFINET port |
| X3 (DP) | Green/Yellow | Off or on | PROFIBUS DP link state on the X3 interface |
Verification Checklist
- Insert compatible SIMATIC Memory Card and confirm MAINT LED does not flash at 2 Hz after power-on.
- Open Online > Accessible nodes; CPU appears with the correct IP and MAC.
-
pingthe CPU IP from the PG/PC command prompt; replies within 1 ms. - Run Online > Download to device > Hardware configuration; completes without error.
- CPU transitions to RUN; the RUN LED is solid green.
- Open Online & Diagnostics > Diagnostic buffer; no entry with "Startup inhibit" or "Memory card" remains.
- For F-CPU: load safety program; F-runtime group reaches the RUN state in the safety view.
- Force a test tag via watch table; force value is applied and acknowledged.
- Power-cycle the CPU; auto-restart into RUN confirms the configuration is now persistent on the card.
Field-Proven Pitfalls
- Card formatted by a different tool. Windows formatting of an SD card to FAT32 will not produce a SIMATIC-readable card. The CPU rejects it with inhibit #1. Always use Siemens-issued cards.
- PROFINET name not assigned. Even when the IP is correct, PROFINET IO devices require a device name. If the CPU is acting as a PROFINET IO controller and a downstream device has lost its name, the SF LED can also indicate "IO fault". This is unrelated to the startup inhibit but visually identical.
- Firewall blocking TIA Portal. The Windows Defender firewall will block the download if the network profile of the PROFINET adapter is set to Public. Switch the profile to Private or add %SystemDrive%\Program Files\Siemens\Automation\Portal V[xx]\bin\S7tmgr.exe to the exception list.
- MRES misapplied. Memory Reset (MRES) clears work memory and re-reads the card. It does not repair a missing or wrong HW configuration; it merely restarts the same diagnostic state. Use MRES after fixing the card, not before.
- Hot-swapping with active PROFINET. Removing the memory card on a running CPU is allowed on firmware V2.6+ but generates an immediate SF and a diagnostic entry; for first commissioning always power down.
- Firmware version mismatch. A card written by a V3.1 CPU cannot be read by a V2.9 CPU. If you replaced the CPU, you must also re-load the project.
Related Diagnostic Entries That Look Similar but Have Different Causes
| Diagnostic entry | Distinguishing clue | Distinct remedy |
|---|---|---|
| Memory card missing | MAINT LED off; slot empty on visual inspection | Insert card |
| Memory card wrong type | Card present but article number is not 6ES7954-8xxx | Replace with Siemens card |
| Memory card wrong content | Card from another CPU or different project | Re-download full project or format card |
| Memory card protected | MAINT LED 2 Hz; write-protect slider engaged | Unlock slider |
| HW configuration not loaded | Card is correct but no project loaded yet | Run hardware download first |
| HW configuration not successfully finished | Card present, project present, but last download was interrupted | Re-download HW configuration, do not power off mid-write |
| No startup | Power-On mode parameter is STOP | Change parameter or perform MRES with mode selector |
When to Escalate to Siemens Support
If the diagnostic buffer retains an "IO configuration error" or "System error in module" entry after the card, HW config, and IP are all confirmed correct, capture the diagnostic buffer as a text file (Online & Diagnostics > Diagnostic buffer > Save as text) and the service data (Online & Diagnostics > Functions > Save service data) before opening a support request via the Siemens Industry Online Support portal. Both files contain information that Siemens engineering requires to identify firmware-level bugs; without them the case is typically closed as “no defect found”.
Standard references for cross-checking:
- S7-1500 Automation System Function Manual (Siemens Support: S7-1500 system manual)
- CPU 1517F-3 PN/DP product page (Siemens Support: 6ES7517-3FP00-0AB0)
- SIMATIC Memory Card catalog (Siemens Support: SIMATIC memory card portfolio)
- TIA Portal help: "Downloading projects to the device" (offline in TIA Portal under Help > Show Help)
FAQ
Why does the S7-1500 refuse to run when the memory card slot is empty?
The S7-1500 stores the hardware configuration, the runtime project, and the safety signature on the SIMATIC Memory Card rather than in onboard flash. Without the card, the CPU cannot reconstruct the configured topology on power-up, so it holds itself in STOP with the inhibit message "Memory card missing, wrong type, wrong content or protected". Insert a compatible 6ES7954-8xx03-0AA0 (or newer) card before the first download.
Does the PG/PC and the CPU 1517F need the same IP address?
No. Two devices cannot share the same IP at the same time. They must share an IP subnet (same network address and same subnet mask) but use different host addresses. A typical pairing is PG/PC 192.168.0.10 and CPU 192.168.0.1 with subnet mask 255.255.255.0. Verify with ping <cpu-ip> from the PG/PC command prompt before the next download attempt.
Can I download hardware and software in one step on a CPU 1517F-3 PN/DP?
Yes, via Online > Download to device > Hardware and software (only changes). On a fresh card the dialog will offer "Download hardware configuration including safety program" after the F-password is supplied. If the safety program is new or modified, complete the F-download in a second pass for safety signature integrity.
What does MRES do on the 1517F, and when should I use it?
MRES (Memory Reset) clears the work memory of the CPU and forces a re-read of the project from the SIMATIC Memory Card. It does not repair a missing card or missing HW configuration. Use MRES only after the card is correctly populated and the HW configuration has been downloaded, typically as the final step before going to RUN. MRES is operated via the mode selector on the front panel (turn to MRES, hold 3 s, release, return to STOP within 3 s).
Why does the SF LED come back on after a successful first download?
Most commonly because a downstream PROFINET IO device has lost its device name or has been swapped. Open Online & Diagnostics > PROFINET diagnostics and check the device list: any module marked "Not reachable" or "Wrong module" requires the IO device to be re-assigned its PROFINET name via Topology > Assign PROFINET device name before the SF clears.
Is a 1517F download different from a non-F 1517 download?
The standard program download is identical. The 1517F additionally requires a safety-program download gated by the F-password; without it, TIA Portal reports "Download aborted" at the very last step. After the safety download, the F-runtime group runs a self-test (typically 5–25 seconds) during which the F-IO are passivated.