WinCC Flexible Multi-User Engineering with STEP 7 on Two PCs

When a control application outgrows a single engineering seat, Siemens classic toolchains (STEP 7 V5.x with Simatic Manager and WinCC flexible) can still be split between two physical PCs without migrating to TIA Portal. The PC that handles the PLC program and the PC that handles the HMI screens can be located on the same network, share a common project tree on a file server, and exchange the symbolic tag interface that links the controller's data block definitions to the panel's tag table. This reference documents the field-proven file-server pattern for this configuration, the symbolic tag integration mechanics, the multi-instance data block addressing rules, and the save-as versioning discipline that keeps older revisions recoverable while new work is being committed.

1. Overview and Engineering Model

WinCC flexible is the engineering tool for SIMATIC Panels (OP 77B, TP 177, TP 277, MP 277, MP 377, and the later Comfort Panels) and for WinCC flexible Runtime panels. STEP 7 V5.x with Simatic Manager is the corresponding controller engineering tool for S7-300, S7-400, and ET 200S stations. The two tools share a tag interface: every PLC tag defined in STEP 7 with a symbolic name and a data block address can be made available to the HMI configuration as a symbolic HMI tag, and the panel runtime uses the same absolute address.

When the engineering is divided between two PCs, the model is straightforward:

• PG #1 (PLC engineer): Runs Simatic Manager, edits the S7 program, defines symbols in the Symbol Table (S7-Program > Symbols), edits DBs and FBs, and compiles.
• PG #2 (HMI engineer): Runs WinCC flexible, edits the project tree (screens, tags, alarms, recipes, area pointers, connections), and rebuilds the runtime file.
• File server: Hosts the STEP 7 project (a directory tree of .s7p, .s7f, .s7l, and symbol files) and the WinCC flexible project (a directory tree rooted at <projectname>.hmi and the workspace *.hmi_workspace).

Both engineers work locally on their PG; changes are saved back to the server. The link between the two halves is the symbolic tag connection, which must be re-established whenever the project is opened on PG #2 if the STEP 7 part has changed.

2. Architecture Options for Distributed Engineering

Three architectures are realistic for the classic toolchain. The choice is dictated by network infrastructure, project size, and the team's version-control discipline.

For most two-engineer teams the file server approach (Option A) is the right answer. It is the configuration documented in the Simatic Manager help and is sufficient when the engineers coordinate their check-ins verbally or via a change log.

3. Prerequisites and Licensing

4. File Server Deployment Topology

The recommended layout isolates the STEP 7 project and the WinCC flexible project under a per-line root. The server directory becomes the single source of truth for both halves of the project.

\\FS01\PROJECTS\LINE_A\
  +- S7_PROJ\                  <-- STEP 7 project, edited by PG #1
  |    +- line_a.s7p
  |    +- S7_PROJ\             <-- Simatic Manager compressed file store
  |    +- hmi_tags\            <-- exported symbol file (optional)
  +- HMI_PROJ\                 <-- WinCC flexible project, edited by PG #2
       +- TP277_S7_300.hmi_workspace
       +- TP277_S7_300.hmi
       +- im\                  <-- compiled runtime files
       +- lg\                  <-- generated logs
       +- pr\                  <-- source screens

An inline SVG of the deployment is shown below.

5. STEP 7 Project Storage on the Shared Server

1. On PG #1, open Simatic Manager and create the project at \\FS01\PROJECTS\LINE_A\S7_PROJ (menu File > New > Project).
2. Insert the S7-300 or S7-400 station (Insert > Station > SIMATIC 300/400 Station).
3. Open the hardware configuration (HW Config) and assemble the rack. Save and compile (Station > Save and Compile). The compiled S7HKP is required by the HMI tag integration later.
4. Open the Symbol Table (S7 Program > Symbols). For every tag that will be exposed to the HMI, declare a symbolic name with a data type and a comment. Example:

5. Compile the S7 program (PLC > Compile and Download Objects, or Save and Compile on the program editor). The symbol information is what WinCC flexible will read.
6. Save the project (File > Save or Ctrl+S). The full *.s7p tree is committed to the server share.

6. WinCC Flexible Project Integration on the HMI Engineering PC

1. On PG #2, install WinCC flexible 2008 SP5. Install the matching HSPs (Hardware Support Packages) for the target panel, e.g. HSP for TP/OP/MP 277/377.
2. Create the WinCC flexible project on the server share: File > New, target directory \\FS01\PROJECTS\LINE_A\HMI_PROJ, panel type TP 277 8" or MP 377 12" as required.
3. Add a connection of type SIMATIC S7 300/400. Set the parameters:
   • Station address = S7 station rack/slot, e.g. rack 0 slot 2 (CPU 314) or rack 0 slot 3 (CPU 416)
   • Cycle acquisition = 1 s for status, 100 ms for control bits
   • Enable area pointers = ticked (required for date/time, PLC job, project ID)
   • Coordination area pointer must point to a free DB (e.g. DB 99) for life-bit supervision
4. Save the project locally first (Ctrl+S) and verify the connection is reachable with Online > Accessible Nodes. Confirm the panel can resolve the S7 CPU's MPI/Profibus/Ethernet address.

7. Symbolic PLC Tag Integration Across the Two PCs

This is the critical step that makes the configuration viable. The HMI engineer needs to use the same symbolic names defined by the PLC engineer. There are two supported methods.

7.1 Method 1 - Direct integration (preferred)

WinCC flexible can read the symbolic tag table from the STEP 7 project directly. On PG #2, in the WinCC flexible tag editor, right-click and choose Insert > Tag from STEP 7. WinCC flexible prompts for the location of the STEP 7 project. Point it to \\FS01\PROJECTS\LINE_A\S7_PROJ. WinCC flexible will read the symbol table and add the symbols to the HMI tag table with the correct absolute address and data type.

• If the STEP 7 project is on a different physical machine and the SMB share is not trusted, copy the S7_PROJ tree to a local working folder on PG #2 first, then point WinCC flexible at the local copy. Refresh after each PLC change.
• After import, the HMI tag table shows both a Symbol (text) and an Address (e.g. DB101,DBX0.0). The HMI engineer should not edit the address manually; edits to the address will break the link.

7.2 Method 2 - Export / import of the symbol table

If the SMB link is unreliable, PG #1 exports the symbol table to a CSV or SEQ file (Symbol Table > Export) and commits it to a shared folder. PG #2 imports the file (WinCC flexible > Tools > Import Symbols). Re-import after every PLC tag change.

7.3 Symbol name length and character set

WinCC flexible limits symbolic tag names to 24 characters and rejects characters outside the Siemens S7 symbol set (A-Z a-z 0-9 _). STEP 7 accepts up to 24 characters per symbol. Both must be aligned before the project starts; renaming after the fact breaks HMI references in every screen, alarm, and recipe.

8. Multi-Instance DB Handling in the Distributed Workflow

Multi-instance data blocks (instance DBs that hold the static data of an FB) are common in structured S7 programs. The HMI engineer must address each instance correctly. There are two approaches.

For two-PC engineering with WinCC flexible, the per-instance DB approach is strongly preferred: each motor, valve, or station gets its own DB and a unique symbolic name (Motor1_Run, Motor2_Run, etc.). The HMI engineer never needs to compute offsets; the symbol import pulls in every instance automatically.

9. Save-As Versioning Discipline

Because Simatic Manager and WinCC flexible have no native version control, the Save As workflow is the engineer's safety net. A practical scheme:

1. At the start of every working day, PG #1 opens the project on the server and immediately File > Save As into a dated sibling folder: \\FS01\PROJECTS\LINE_A\_ARCHIVE\S7_2025-03-14_AM.
2. PG #2 follows the same pattern: \\FS01\PROJECTS\LINE_A\_ARCHIVE\HMI_2025-03-14_AM.
3. After any major milestone (new screen, new FB, new safety function), an additional Save-As snapshot is taken.
4. Retain the last 10 daily snapshots and the last 5 milestone snapshots. Older ones can be compressed to .zip on the server.
5. Never edit inside an archive folder. Archives are read-only by intent; the working copy is always the current project root.

For larger projects, automate the snapshot with a small batch script run from the task scheduler on PG #1:

@echo off
set DATE=%date:~-4%-%date:~3,2%-%date:~0,2%
xcopy "\\FS01\PROJECTS\LINE_A\S7_PROJ" "\\FS01\PROJECTS\LINE_A\_ARCHIVE\S7_%DATE%" /E /I /Y /R

10. Coordination, Locking, and Change Management

The file server pattern relies on human coordination. A simple change log file (CHANGELOG.txt in the project root) prevents collisions:

[2025-03-14 09:00] PG1 - added FB205 (ValveFB), inserted DB201-DB204, new symbols VALVE_x_Open, VALVE_x_Closed
[2025-03-14 09:15] PG1 - compiled HW Config, ready for HMI import
[2025-03-14 09:30] PG2 - imported symbols, added 4 new valve tags to screen "ValveOverview", rebuilt runtime
[2025-03-14 09:45] PG1 - changed Motor1_Speed to REAL, no DB layout change
[2025-03-14 10:10] PG2 - no change required, symbolic link updated automatically

Conventions to enforce:

• PLC changes are committed in the morning, HMI changes in the afternoon (or vice versa, but never interleaved by both engineers within the same hour).
• A PLC change that renames, deletes, or changes a data type of a symbol must be flagged in the change log so the HMI engineer knows to re-import the symbol table.
• Use the Simatic Manager Reference / Cross-reference tool to see which symbols are still referenced before deleting them.

11. Verification, Compilation, and Consistency Checks

Before the runtime is built and transferred to the panel, run the following checks.

1. STEP 7 side (PG #1):
   • PLC > Compile and Download Objects with full compile. No warnings about inconsistent DB structure or unresolved symbols.
   • Symbol Table > Consistency Check. All HMI-relevant symbols must be unique, properly addressed, and within an existing DB.
   • HW Config > Station > Consistency Check if a hardware change was made.
2. WinCC flexible side (PG #2):
   • Project > Compiler > Check Consistency. All tag references must resolve.
   • Tools > Cross Reference for the tag table: every HMI tag used in screens, alarms, and recipes must point to a valid PLC symbol or a valid local tag.
   • Project > Generate Runtime. No compile errors. The generated runtime file is written to the project tree's im folder.
3. Runtime transfer (PG #2, with the panel on the network):
   • Transfer > Transfer over Ethernet/Profibus/MPI. Enable Transfer on the panel (Control Panel > Transfer).
   • After transfer, watch the panel boot and confirm the HMI tag values reflect the current PLC state.
4. Final online test with S7-PLCSIM (optional):
   • Run PLCSIM on PG #1, simulate I/O, observe the panel's screen updates in real time.

12. Troubleshooting Matrix

13. Field-Commissioning Notes

• When the project is small enough to live entirely on the local PG, do that first, then move the tree onto the share once both engineers confirm the workflow.
• Disable Windows Defender real-time scanning on the engineering folders to avoid the 15-30 second scan that delays Save on first commit of a new project. Re-enable after the project is settled.
• Set the SMB server signing to required (Server 2016+ default) - Simatic Manager and WinCC flexible both work with signing on.
• Schedule server-side VSS snapshots every 6 hours during the project, retain 14 days. This is a safety net beyond the Save-As discipline.
• When the project must be hand-carried to a customer site, archive the entire LINE_A folder with WinRAR or 7-Zip (no compression for large STEP 7 files; store-only mode is faster). Avoid cloud sync tools (Dropbox, OneDrive) on the engineering folder - they corrupt the lock-file logic.

14. When to Migrate to TIA Portal

The file server pattern works for the classic toolchain, but TIA Portal's multi-user engineering is more robust: it has project server mode, automatic merging, and a single integrated tag model across PLC and HMI. The migration decision depends on:

• Panel family: Comfort Panels and WinCC Runtime Advanced/Professional are TIA-only. If the target is TP 277 or older, stay on WinCC flexible.
• Controller family: S7-1500 and ET 200SP require TIA Portal.
• Team size: Three or more engineers editing the same project line strongly favour TIA Portal server mode.
• Long-term support: WinCC flexible 2008 SP5 was the final release. New SPs and security patches end in 2020+. See the TIA Portal - WinCC Engineering Manual for the recommended successor.

FAQ