STEP 7 v5.5 Download Button Greyed Out: PCS7 Project Fix

1. Problem Statement

After launching SIMATIC Manager (STEP 7 V5.5) and opening an existing or newly created S7 project, the engineer cannot download logic changes to the target CPU. The following symptoms are reported:

• Toolbar Download button on the LAD / FBD / STL / SCL editor of FC, FB, OB, DB, UDT, SFC, or SFB is greyed out.
• Menu path PLC > Download (English) or Zielsystem > Laden (German) is disabled.
• Menu path PLC > Download to Target System (full project download) is greyed.
• Right-click context menu on a block in the project tree shows no Download entry.
• Save and compile succeeds but Download remains inactive.

The behavior persists after creating a brand-new empty project. The same project opened in STEP 7 V5.4 downloads normally. Platform context in the original report was Windows XP SP3 on a Dell Latitude E6500 with STEP 7 V5.5 + SPx, but the cause is software-only and reproducible on any host that meets the STEP 7 V5.5 system requirements.

2. Root Cause: Project Use Attribute Stamped as PCS 7

Every S7 project carries a project-level attribute that declares which engineering toolset owns the project. In SIMATIC Manager this attribute is shown in the project Object Properties dialog as the Use: drop-down list.

When STEP 7 V5.5 is installed from a PCS 7 installation DVD, or when PCS 7 engineering tools are installed after STEP 7 on the same workstation, the project attribute is written as PCS 7 rather than STEP 7. PCS 7 enforces a different download workflow:

• CFC, SFC, and S7 GRAPH charts must be routed through the PCS 7 Maintenance view.
• SFC instance bindings and WinCC archive tags must be kept consistent across the plant hierarchy.
• Standard STEP 7 download paths can break the plant view or leave the asset descriptor database inconsistent.

For that reason, STEP 7 V5.5 honors the project attribute and disables PLC > Download, PLC > Download to Target System, and the toolbar Download button so the engineer cannot make an inconsistent download outside the PCS 7 workflow. This is intentional behavior, not a bug, and is documented in the SIMATIC Manager help under Use PCS 7 project.

3. Diagnostic Procedure

Before changing anything, verify that the cause is the Use attribute and not one of the other common greyed-out-download causes:

1. Open SIMATIC Manager and load the suspect project.
2. In the left-hand project tree, click the project root (the file-drawer icon at the top of the tree, labelled with the project name).
3. Right-click and select Object Properties (German: Eigenschaften).
4. Open the Use drop-down list inside the dialog.
5. Read the displayed value:
   • If the value is PCS 7, the download restriction is enforced by the PCS 7 project flag - apply the fix in section 4.
   • If the value is STEP 7, the cause is elsewhere. Proceed to section 9 (Other Causes of a Greyed-Out Download).

Cross-check: if STEP 7 V5.4 is available on a parallel machine or in a virtual machine, copy the project to that environment and confirm the download path is active there. If V5.4 allows the download and V5.5 does not, the project flag is confirmed as the cause.

4. Resolution: Reset the Use Property to STEP 7

1. In SIMATIC Manager, select the project root in the left-hand tree.
2. Right-click and open Object Properties.
3. In the Use drop-down, change the selection from PCS 7 back to STEP 7.
4. Click OK. SIMATIC Manager writes the updated attribute into the project global settings and updates the project registry entry.
5. Close and reopen the project to refresh cached flags. SIMATIC Manager caches the Use attribute on project open; in-place edits sometimes require a project reload.
6. Open any FC, FB, OB, DB, UDT, SFC, or SFB and confirm:
   • Toolbar Download button is active (no longer grey).
   • Menu PLC > Download and PLC > Download to Target System are enabled.

5. Controlled Download After Reset

After the Use flag has been corrected, perform a controlled download to the target CPU. The recommended sequence for an S7-300 / S7-400:

1. Establish the online connection. Set the PG/PC interface to the correct adapter (MPI, PROFIBUS, or TCP/IP) under Options > Set PG/PC Interface.
2. Use PLC > Download to Target System if multi-block changes have been made (OB1 plus FB plus DB set). Place the CPU in STOP first by toggling the mode switch.
3. Use PLC > Download (single-block download) for targeted FC / FB / DB updates. The dialog shows Download block to target CPU or Download to memory card.
4. For S7-300 CPUs without a memory card, restart the CPU in RUN after a STOP download using PLC > Cold Restart or PLC > Hot Restart.
5. Verify on the CPU front panel: RUN LED solid, STOP LED off, no SF / BF errors.

6. Why STEP 7 V5.4 Was Not Affected

STEP 7 V5.4 (and earlier versions) ignore the PCS 7 flag stored in the project header and allow the standard download path even when the attribute reads PCS 7. STEP 7 V5.5 introduced stricter enforcement of the project type flag to prevent inconsistent downloads that can corrupt a PCS 7 plant configuration:

• V5.5 added an integrity check on project open that compares the Use attribute against the active license and the installed engineering toolset.
• If the Use attribute is PCS 7 and the installed toolset is plain STEP 7, the download path is disabled and a non-blocking informational message is logged to the SIMATIC Manager trace.
• V5.4 lacks this check and silently allows the download, which is why the same project works under V5.4 but appears locked under V5.5.

7. Why a New Project Is Also Locked

SIMATIC Manager reads the default Use value from a per-user project template. The template location is:

If STEP 7 V5.5 was installed from a PCS 7 DVD, or if PCS 7 V7.x / V8.x engineering tools were installed afterward, the template file is overwritten with Use set to PCS 7. From that point on, every project created via File > New Project inherits the PCS 7 attribute. Uninstalling and reinstalling STEP 7 V5.5 from a plain STEP 7 installation DVD restores the template default.

8. Registry-Level Override

For workstations where STEP 7 V5.5 cannot be reinstalled (locked-down shop-floor PCs, validated systems, DCS engineering seats), the default can be changed in the Windows registry. Close SIMATIC Manager before editing.

Default template override (new projects):

[HKEY_CURRENT_USER\Software\Siemens\Automation\Projects\STEP7\Templates]
"ProjectType"="STEP7"

Set ProjectType to STEP7 to force new projects to default to STEP 7 instead of PCS 7. Existing projects still need their per-project Use attribute flipped through Object Properties as described in section 4.

Per-project override (single project):

[HKEY_CURRENT_USER\Software\Siemens\Automation\Projects\<project-name>]
"Use"="STEP7"

9. Other Causes of a Greyed-Out Download Path

If the Use attribute is already STEP 7 and the download path is still disabled, check the following common causes:

10. Related Symptoms From the Same Root Cause

11. Verification Checklist After Fix

1. Open Object Properties on the project root and confirm Use = STEP 7.
2. Open any FB / FC and confirm the Download toolbar button is active.
3. Confirm PLC > Download and PLC > Download to Target System are both enabled.
4. Establish an online connection via PLC > Display Accessible Nodes and confirm the CPU is listed.
5. Click PLC > Download on a single block change - target CPU should accept the block and the block timestamp should refresh in the online view.
6. For multi-block or OB1 changes, stop the CPU (mode switch to STOP) and execute PLC > Download to Target System. CPU restarts in RUN after completion.
7. Check PLC > Module Information > Diagnostic Buffer for Download completed entries; absence indicates an online-connection problem, not the Use flag.
8. Save the project (File > Save) and close SIMATIC Manager. Reopen and confirm the Use attribute has persisted.

12. Edge Case: Projects That Must Stay PCS 7

If the project is genuinely a PCS 7 plant with CFC / SFC charts, S7 GRAPH sequences, and WinCC archive bindings, the Use attribute must remain PCS 7. In that case, the download must be initiated through the PCS 7 Maintenance view or via the CFC / SFC editor, not through the standard STEP 7 block editor. Forcing Use = STEP 7 on a real PCS 7 project can:

• Break the plant view hierarchy.
• Lose SFC instance bindings to the automation library.
• Corrupt WinCC archive tag references.
• Desynchronize the asset descriptor database from the live PLC.

Always confirm with the plant engineer that the project is a pure STEP 7 project before applying this fix. On a greenfield S7-300 / S7-400 cell with no PCS 7 integration, Use = STEP 7 is correct.

13. Compatibility Notes for STEP 7 V5.5

• Operating systems: Windows XP SP3 (32-bit), Windows 2003 Server SP2 (32-bit). Windows 7 (32-bit) is supported only with STEP 7 V5.5 + SP2 + K5.5.4 and later hotfixes, or via Windows XP Mode. Windows 10 / 11 are not officially supported for V5.5.
• CPU families supported: S7-200 (via Micro/Win add-on), S7-300 (CPU 312 through CPU 319F), S7-400 (CPU 412 through CPU 417), C7, ET 200S / ET 200pro CPUs, WinAC RTX / Slot.
• License key: STEP 7 V5.5 requires a parallel port, USB, or ALM license key. Missing or unrecognized license will grey out the download path even on a valid STEP 7 project - check Start > SIMATIC > STEP 7 > AuthorsW.
• Project interoperability: STEP 7 V5.5 can open V5.4, V5.3, and STEP 7 V5.5 SPx projects. Projects upgraded to PCS 7 V7.x or V8.x cannot be cleanly downgraded - the Use flag must be migrated through Object Properties on the project root.
• Hotfix relevant to download integrity: K5.5.4 fixed a project-type flag detection bug in V5.5 + SP2 that could mark non-PCS 7 projects as PCS 7 under certain locale settings. Install K5.5.4 or later on greenfield installations.

14. Inter-Version Project Migration

When migrating a project from STEP 7 V5.4 to V5.5, perform the following checks before the first download:

1. Open the project in STEP 7 V5.5 and confirm the Use attribute is STEP 7 (not PCS 7).
2. Re-compile all blocks (Program > Compile All) - V5.5 compiles more strictly and will surface type mismatches that V5.4 ignored.
3. Re-run HW Config to confirm the hardware catalog matches. V5.5 ships newer HSPs that may have changed CPU firmware references.
4. Save the project under the V5.5 SPx format (File > Save As) to write the Use attribute to the new project registry key.

When migrating from V5.5 back to V5.4 (uncommon, but required for older test setups):

1. V5.4 reads the V5.5 project file and accepts it without conversion.
2. If the Use attribute is PCS 7 on a V5.4 station, V5.4 ignores it and downloads normally.
3. CPU type upgrades that V5.5 allows (e.g. CPU 317-2 PN/DP V3.3) may not be accepted by V5.4; downgrade the CPU type in HW Config before saving in V5.4.

15. Field Tip: Cleaning Up After a PCS 7 Co-Installation

If a workstation has both STEP 7 V5.5 and PCS 7 V7.x / V8.x installed, the default project type toggles between PCS 7 and STEP 7 depending on which tool was launched last. To keep STEP 7 V5.5 as the default, export the registry template key after a clean STEP 7 session:

Import the saved .reg on each workstation after PCS 7 sessions to restore the STEP 7 default. For batch deployment, push the .reg through Group Policy Preferences (GPP) or a login script that runs only for engineering users.

16. Diagnostic Buffer and Trace Interpretation

When the download path is greyed out and the Use attribute is confirmed STEP 7, the SIMATIC Manager trace gives a definitive answer. Open a command prompt and tail the trace:

Common trace messages for the symptom:

17. Anti-Virus and Group Policy Interference

Common field issues where the Use attribute is correct but the download is still greyed:

• Anti-virus real-time scan quarantining .s7p, .s7l, .s7b files on open - the project loads but compiles with errors and the download is disabled.
• Windows Defender Controlled Folder Access blocking writes to the project folder.
• Group Policy enforcing read-only on user profile directories - the project defaults to read-only on open.
• Disk encryption (BitLocker, VeraCrypt) pausing writes - the SIMATIC Manager trace shows Access denied on commit.

Resolution: add the project folder and the SIMATIC Manager installation path (typically C:\Program Files\Siemens\Automation) to the AV exclusion list, exclude the folder from Controlled Folder Access, and confirm GPO does not enforce read-only on user folders.

18. Safety and Operational Notes

19. Prevention and Best Practices

• Install STEP 7 V5.5 from a plain STEP 7 DVD on engineering workstations, not from a PCS 7 DVD.
• If PCS 7 is co-installed, separate the engineering workstations - STEP 7 only on one set, PCS 7 only on another, and a small set with both for commissioning only.
• Apply K5.5.4 or later on every STEP 7 V5.5 + SP2 install to avoid the locale-driven Use flag bug.
• Document the project Use attribute in the project header so commissioning engineers know whether the project is plain STEP 7 or PCS 7.
• Add the Object Properties > Use check to the standard project handover checklist.
• For multi-engineer projects, export and version-control the project registry key along with the .s7p file so the Use attribute is reproducible.

20. FAQ