Transferring WinCC Modifications from PCS 7 ES to OS Stations

Overview: ES, OS, and Server Roles in PCS 7

In a Siemens PCS 7 plant, the Engineering Station (ES) hosts the SIMATIC Manager / STEP 7 project with the WinCC Explorer and the WinCC Graphics Designer. The Operator Station (OS) runs WinCC Runtime and serves the operator screens. A single ES project can compile OS images for one or more OS servers and many OS clients. When a picture, tag, archive selection, or alarm class is added on the ES, that change must be propagated to every OS Runtime that needs to display it. There are three propagation paths that engineers actually use in the field:

• OS Compile + OS Download through SIMATIC Manager — the canonical PCS 7 path. This pushes the WinCC project database (tags, alarms, archives, picture references, scripts) into the OS server's WinCC project in one operation.
• Picture (.PDL) copy — manually copy updated GraCS picture files into the OS server's WinCC project folder and restart WinCC Runtime. Useful for design-only changes that introduce no new tags, no new archive selections, and no new message classes.
• Project duplication — copying the entire S7 project folder to a second machine. Acceptable for migrating a standalone ES to a new OS, but not for routine change deployment.

This article focuses on the first two paths and the field traps that break them: missing trends, blank IO fields after a picture copy, the dreaded No connection to data server message, and archive license overruns.

Prerequisites Before Any ES→OS Transfer

1. Network reachability. The ES and OS machines must be on the same plant network (terminal bus) and reachable by TCP/IP. OS servers usually have a fixed IP and the ES must have the OS in its WinCC Explorer > Computer list with the matching computer name. A ping from the ES to the OS by computer name is the fastest sanity check.
2. Version parity. The PCS 7 version on the ES must match the OS Runtime version. Mismatches between PCS 7 V8.0, V8.1, V8.2, V9.0, V9.1, or later will reject the download before any file is transferred. Use only OS images generated from an ES of the same major release.
3. Clean OS compile. The S7 project must compile OS without errors. Open the OS in WinCC Explorer on the ES and select File > Compile > OS (or right-click OS > Compile OS). Resolve any Tag not connected or Picture not found warnings before attempting the download. A clean compile is non-negotiable; a partial compile will produce an OS image that compiles on the ES but fails to start on the server.
4. Runtime stopped or in maintenance. The OS Runtime must be stopped or the OS server placed in maintenance before download; otherwise WinCC Runtime locks the project files and the download will fail with Project is locked. SIMATIC Manager can stop Runtime automatically as part of the download sequence if the user grants the prompt.
5. User rights. The ES account performing the download must be a member of the SIMATIC HMI / SIMATIC NET group on the OS, or an administrator. Otherwise the WinCC service will refuse the connection and the download will hang at the Establishing connection step.
6. Licensing. Trend and archive licenses are tied to the OS server's license stick or soft container. Trend loss after a download almost always points to a license or archive-path mismatch, not to a missing tag.

Recommended Path: OS Compile and OS Download from the Component View

This is the path that pushes every dependent WinCC object — tags, picture references, archive configuration, message classes, Global Scripts, and faceplate instances — to the OS server in one operation. It is also the only path that simultaneously updates the OS server's project database so clients pick up changes at the next picture call.

1. On the ES, open SIMATIC Manager and switch to Component View (View > Component View).
2. Locate the OS folder under the S7 program. The folder is named after the OS computer (for example OS_Ref, OS_Server_1, OS_Client_1). If your project has a redundant OS pair, two folders will be visible — one for each server.
3. Right-click the OS folder that contains the modified WinCC project.
4. Select PLC > Download. SIMATIC Manager opens a dialog prompting for the target computer; choose the matching OS server. Confirm the target computer name matches WinCC Explorer > Computer > Properties > Computer Name on the OS.
5. Confirm the Stop Runtime prompt. The OS Runtime shuts down, the project files are transferred, and Runtime restarts automatically when the download completes.
6. Wait for the WinCC Runtime activation prompt or for the OS faceplate to report Runtime active. Total transfer time is typically two to ten minutes depending on project size and network bandwidth. A 50 MB WinCC project over a 1 Gbit/s terminal bus usually completes in under three minutes.

Picture-Only Path: Copying Updated .PDL Files

When the ES change is purely cosmetic — a new button, a recolored bar, a repositioned faceplate, with no new tags, no new archive selections, and no new message classes — a direct file copy is faster than a full OS download. The default project path on the ES is:

Steps:

1. On the ES, copy the modified .PDL file from the source OS folder above.
2. On the OS server, navigate to the matching path: C:\Program Files\SIEMENS\STEP7\S7proj\<project_name>\wincproj\<OS_name>\GraCS\
3. Paste the .PDL file, overwriting the older version. The file name must match exactly (WinCC is case-sensitive on the picture tree).
4. Stop WinCC Runtime on the OS server (WinCC Explorer > File > Stop Runtime, or via the OS service console). Picture files are loaded into a runtime cache and the cache is only flushed on Runtime start.
5. Restart WinCC Runtime. The new picture is loaded into the graphics cache and made available to all connected OS clients.

Server vs. Client Architecture Considerations

PCS 7 OS deployments fall into two common topologies:

• OS Server + OS Clients: the server holds the WinCC project, archives, and tag database. Clients only render pictures served by the server. After modifying the ES, you must compile and download to the OS Server. Clients pick up changes at the next picture change or after their own WinCC restart — they do not require a separate download as long as the server is up.
• Standalone OS (no server): a single machine runs both server and client roles. Compile and download target that one OS. The picture-copy path may be used only for design changes with no new tags.

If you are unsure whether a server exists in your project, open WinCC Explorer on the OS and check Computer > Properties. A machine whose startup mode is WinCC Runtime (server) is the server; machines set to WinCC Runtime (client) are clients. A server with the Redundant flag set is a member of a redundant OS pair; both servers must be updated.

NetPro and AS–OS Connection

The OS talks to the AS (Automation Station, the S7-400 / S7-1500 CPU) through connections defined in NetPro. If trends vanish and the message No connection to data server appears immediately after an OS download, the OS has lost its AS connection. Verify:

1. In SIMATIC Manager on the ES, open NetPro and confirm that the OS server has an S7 connection to the AS, with the correct rack/slot and TSAP.
2. Compile and download NetPro to both the AS and the OS (Network > Compile and Check All, then download to AS and OS).
3. On the OS, open WinCC Explorer > Tag Management > SIMATIC S7 PROTOCOL SUITE > TCP/IP and confirm the connection status is green. Yellow indicates initialization; red indicates no connection.
4. From the OS command line, run ping <AS_IP> and verify round-trip time below 5 ms on the terminal bus.

Troubleshooting Matrix: Trends / Graphs Disappeared After OS Download

When the trend controls stop drawing after an OS download, work through the following matrix in order from cheapest to most invasive:

Redundant OS Server Pair Handling

A redundant PCS 7 OS pair (OS_Server_1 + OS_Server_2) requires a coordinated download to keep both servers at the same project level:

1. Compile OS on the ES. The compile produces a single OS image shared by both redundant servers.
2. Stop WinCC Runtime on the standby server first (the server whose Status in WinCC Explorer shows Standby).
3. Download the OS image to the standby server.
4. Restart Runtime on the standby server and confirm it returns to Standby state.
5. Trigger a failover (or wait for the next scheduled failover) so the standby becomes the master.
6. Repeat steps 2-4 on the now-standby server.

Failing to keep both servers in sync produces a redundancy alarm the next time the master fails over to the stale image.

License Considerations in Detail

PCS 7 uses three license pools on the OS server: RT (Runtime base), Tags (process tag count), and Archives (archive tag count). When the ES pushes a new archive tag, the OS compile increments the required archive tag count by one. If the license count is already saturated, the new archive tag is accepted into the configuration but the archive server refuses to log it, and the trend control shows a flat line at zero.

Diagnostic path: on the OS, open WinCC Explorer > Tools > License Analysis. The dialog reports licensed vs. configured counts for every license pool. If Archive tags used > Archive tags licensed, either remove archive selections for obsolete tags or extend the license.

Verification Procedure

After every ES–OS transfer, validate the change end-to-end:

1. On the OS, confirm Runtime is active (WinCC Explorer status bar shows green).
2. Open the modified picture on the OS client. Verify the new graphic elements appear and animations respond.
3. Click into the trend control and confirm the curve draws. Toggle between 1 h, 8 h, 24 h windows.
4. Trigger a tag change from the AS (for example via a forced variable in STEP 7) and confirm the OS faceplate updates within one second.
5. Trigger a process alarm and confirm the message line and the archive entry are populated.
6. Open WinCC Explorer > Tools > Status of Connections and verify all S7 connections are OK.
7. From an OS client, call the picture by name and confirm the server delivers the updated .PDL without restarting the client.

Cross-Reference: WinCC on Unified Comfort Panels (TIA Portal)

Although the field report is PCS 7 (legacy WinCC), the underlying transfer model also applies to TIA Portal Unified Comfort Panels. The transfer flow there is:

1. On the panel, open Control Panel > Service and Commissioning > Transfer and confirm Enable transfer is on.
2. Configure the connection mode: Ethernet or USB. For Ethernet, set a static IP and confirm the ES can ping the panel.
3. On the TIA Portal ES, right-click the HMI device, select Compile > Software (full), then Download to device > Software (full).
4. The panel restarts into transfer mode and accepts the project. A reboot is part of the normal transfer sequence.

Documentation for this path is published by Siemens at the TIA Portal Unified Comfort Panels — Transferring a project with WinCC reference page.

Common Field Pitfalls

• Forgetting the picture-copy path is design-only: copying a .PDL that references a new tag will display the picture but the new tag remains undefined. The IO field shows ###### or stays empty.
• Compiling OS on the wrong OS folder: SIMATIC Manager can hold several OS folders (one server, multiple clients, redundant pair). Compiling the wrong folder will deploy unchanged files.
• Not stopping Runtime: a download attempted while Runtime is running will fail with Project is locked. The correct procedure is to allow SIMATIC Manager to stop Runtime as part of the download.
• NetPro out of sync: adding a new AS connection on the ES but not re-downloading NetPro to the AS breaks the AS–OS path even if the WinCC project compiles cleanly.
• Time mismatch between ES and OS: trends depend on time-stamped archives. A clock skew greater than five seconds between AS and OS will produce gaps in trend curves after a download.
• Soft container migration: moving an OS license from a USB stick to a soft container requires a clean OS download so the license service re-binds to the new container path. Skipping this step leaves the server in demo mode for 24 hours.
• Domain vs. workgroup: if the OS is in a Windows workgroup and the ES is in a domain, the WinCC service must log in with a local account. Domain credentials will fail the license check and Runtime will refuse to start.

Quick-Reference Checklist