Fix PCS 7 Runtime Group Does Not Exist PLCSIM Download Error

Fix PCS 7 'Runtime Group Does Not Exist' Error During PLCSIM Chart Download

The Runtime Group Does Not Exist error stops a PCS 7 S7 program download to S7-PLCSIM even when compilation reports zero errors and all @Charts are re-generated. The failure is not a compile fault — it surfaces only when STEP 7 / PCS 7 tries to load the resulting system data to the simulated CPU. The reason is structural: the S7 program has lost one or more runtime groups that the PCS 7 OS or the CFC editor must bind to during the download handshake. This reference walks through the runtime group architecture, the exact failure path, the diagnostic checklist, and the field-proven fix sequence.

1. Technical Background: Runtime Groups in PCS 7

A runtime group is a CFC/SFC construct that binds a logical task (cyclic interrupt, time-of-day interrupt, startup) to an organisation block (OB) of the S7 CPU. PCS 7 ships with a fixed set of standard runtime groups that map onto the process OB layer:

The @Charts container is a system-level CFC chart folder that is automatically generated by the PCS 7 plant view. It does not contain user logic; it contains the runtime group objects and the OS variable handover that WinCC Runtime needs to resolve when the OS server activates. When the CFC compiler runs Entire program → Compile and download objects, it expects every referenced runtime group to be present in the S7 program symbol table.

2. Symptoms and Error Context

The error appears under very specific conditions:

• The S7 project compiles without warnings or errors after a full Entire program compilation.
• All @Charts have been regenerated in the S7 program tree (visible in SIMATIC Manager under the chart container).
• The user initiates PLC → Download to a S7-PLCSIM instance that is already running and in STOP or RUN-P.
• STEP 7 reports a dialog titled Download to target system — error, with the message body: "Runtime group does not exist" (German original: Laufzeitgruppe existiert nicht).
• The download aborts before any block (OB, FB, DB, SFB) is transferred to the simulated CPU.

The wording is generic — STEP 7 does not name the missing runtime group — so the engineer must reconcile the S7 program structure manually.

3. Root Cause Analysis

The error is raised by the STEP 7 download service (s7onlinx.dll) when it walks the S7 program header for the target CPU and cannot match the runtime group identifier (an internal CFC pointer) to a corresponding block in the offline program. Five root causes account for 95 % of field reports:

1. Deleted or missing @Charts container after a manual cleanup. The user re-creates the chart folder but does not regenerate the runtime group system data via CFC → Charts → Insert Runtime Group.
2. Master data library mismatch. The PCS 7 master data library used during the last compile differs from the one currently mounted. Runtime group symbols reference the library version and fail to resolve.
3. Incomplete "Compile and download objects" pass. Only the user charts were compiled; the system chart partition (@Charts) was skipped because of a target system filter rule.
4. PCS 7 OS project not yet present. When the OS project is missing, the CFC compiler omits the OS linkage runtime group from the generated S7 program. STEP 7 then tries to download a runtime group identifier it never generated.
5. PLCSIM instance wrong version. A PLCSIM V5.4 instance is paired with PCS 7 V9.x blocks that reference runtime groups not present in the older PLCSIM firmware stub.

4. Pre-Download Verification Checklist

Run the following checks before every PLCSIM download. Each pass reduces the chance of a partial download:

5. Diagnostic Procedure

Follow this procedure in order. Stop after the first step that resolves the issue.

Step 5.1 — Confirm the missing runtime group identity

1. Open the S7 program in SIMATIC Manager.
2. Right-click Charts → Charts of the S7 program.
3. Switch to the Runtime groups tab at the bottom of the CFC editor.
4. Compare the listed runtime groups against the canonical list in Section 1 of this article.
5. Mark every missing group. These are your suspects.

Step 5.2 — Read the STEP 7 download log

Activate the verbose download log via Options → Settings → Online → Trace. Reproduce the download and inspect %TEMP%\s7logs\*.log. Search for the pattern LZG (German abbreviation for Laufzeitgruppe) or RTG for the English keyword. The line above the error names the group.

Step 5.3 — Inspect the offline S7 program symbol table

1. Open S7 Program → Symbols.
2. Filter for entries beginning with RG_ or RTG_.
3. Cross-check each entry against the runtime groups identified in Step 5.1.
4. A missing symbol entry confirms the CFC compiler did not emit the runtime group header for that group.

Step 5.4 — Verify the master data library version

1. Open the PCS 7 plant view.
2. Right-click the S7 program → Properties → PCS 7 tab.
3. Note the Master data library path and version.
4. Compare with the library mounted under Options → PCS 7 → Library. Mismatch → remount.

6. Solution Path: Restore Runtime Groups

Solution A — Insert missing runtime group manually

1. Open the CFC editor for the S7 program.
2. Right-click in the chart canvas → Insert runtime group.
3. Choose the OB that maps to the missing group (e.g. OB35 → Runtime 1).
4. Set the cycle time to the PCS 7 standard for that group (see Section 1 table).
5. Save the chart. The @Charts system data is regenerated.
6. Run Charts → Compile → Entire program again.
7. Download to PLCSIM.

Solution B — Force regeneration of @Charts

1. Close all CFC / SFC editors.
2. In SIMATIC Manager right-click the S7 Program → CFC → Generate @Charts.
3. Wait for the regeneration log. It should list each runtime group as "created" or "updated".
4. Recompile entire program.
5. Retry the download.

Solution C — Recreate the OS project linkage

1. Plant view → right-click the hierarchy node → Insert new object → WinCC OS.
2. Open OS Project Editor and confirm the server assignment.
3. Recompile Entire program with OS (this is the option that re-emits the OS linkage runtime group).
4. Download again.

Solution D — Match PLCSIM firmware to PCS 7 blocks

1. Note the MLFB of the simulated CPU in HW Config.
2. Open S7-PLCSIM and select the matching firmware version (e.g. CPU 417-4 V4.5 for PCS 7 V8.2).
3. Restart PLCSIM, reset to factory defaults.
4. Repeat the download procedure.

7. PLCSIM-Specific Considerations

S7-PLCSIM V5.4 emulates an S7-400 station. PCS 7 V9.0 and later expect OB83 / OB85 / OB121 runtime group support that PLCSIM exposes only from build V5.4 SP5 onward. If the PLCSIM build is older:

• Upgrade to S7-PLCSIM V5.4 SP7 or later via the PCS 7 installation media or the Siemens online software delivery.
• Confirm the PLCSIM instance is started with administrator rights; Windows UAC can block the RPC handshake used by STEP 7 download.
• Disable any third-party firewall rules on TCP port 102 (ISO-on-TCP) and TCP port 1030 (RFC 1006 extension). The Siemens Support Entry 88780011 (WinCC Runtime download) lists the same port prerequisites and is a useful cross-check.

PLCSIM supports only one active download session. If a previous download was interrupted, the simulated CPU may be in defective state. In that case:

1. PLCSIM → MRES to clear memory.
2. Switch to STOP.
3. Retry the download.

8. Related OS Download Errors

Engineers frequently mix the runtime group download error with WinCC OS loading errors. The Siemens FAQ at Siemens Support Entry 88780011 — WinCC Runtime Professional download checklist lists the canonical OS-load prerequisites:

• Engineering station and operator station must be in the same Windows domain or use matching local accounts.
• The SIMATIC WinCC Explorer service must be running on the operator station.
• DCOM and RPC ports must be open between the two stations.
• The OS project must be compiled before download; partial compilation raises an OS-side equivalent of the runtime group error.
• The CCProjectMgr.exe activator must have write access to the project path.

These checks apply only when the failure is on the OS side, not on the S7 / PLCSIM side. Diagnose the boundary first, then apply the matching fix path.

9. Verification Steps After the Fix

1. Download completes without dialog errors.
2. Open the online view of the S7 program: PLC → Monitor/Modify.
3. Confirm each runtime group is present on the CPU by inspecting CPU → Operating mode → Information → OB usage.
4. Switch PLCSIM to RUN-P and observe the cyclic OBs fire at the configured intervals.
5. In the OS runtime, open the process picture and confirm the variables resolve (no red question marks).

10. Prevention and Best Practices

• Never delete @Charts manually. Use CFC → Charts → Delete runtime group only, and only after the corresponding OB is decommissioned in HW Config.
• Use the PCS 7 Version Cross Manager to validate the master data library at every project promotion.
• Compile entire program before every download. Partial compilation can mask a missing runtime group header until the download pass.
• Maintain a project template with the standard runtime groups pre-populated, so new S7 programs start with the correct structure.
• Document the PLCSIM build in the project README so engineers do not roll the firmware back inadvertently.
• Apply Siemens hotfixes. The original report referenced Siemens Technical Forum thread 1739-20, which is pinned to the PCS 7 V8.2 hotfix bundle that first corrected the runtime group regeneration defect.

11. Troubleshooting Matrix