Optimizing Performance and Eliminating Network Delays in PCS 7 Multi-User Engineering

Severe performance lag (30–90 second delays when opening charts or compiling) on PCS 7 Engineering Station (ES) clients in Multi-User Engineering is caused by direct remote database access over Windows SMB file shares, poor network latency, or DCOM security inspection. To resolve this, adopt the certified 'Divide and Merge' multiproject workflow where engineers check out individual subprojects locally, ensure dedicated 1 Gbps low-latency terminal bus connections between ES clients and the master ES, disable Windows SMB signing/encryption on engineering network shares, and verify that Simatic Shell communicates over the correct network adapter.

Executive Summary

Large-scale process control projects rely on Multi-User Engineering, allowing multiple automation engineers to simultaneously configure automation stations (AS), program CFC charts, and engineer WinCC operator stations. However, when multiple ES clients access a single centralized project shared across an office or plant network, engineers frequently complain that SIMATIC Manager becomes sluggish, opening charts freezes the UI for over a minute, and cross-reference queries stall. This issue arises because STEP 7 uses an indexed file-based database architecture that generates thousands of small synchronous file I/O requests. This guide explains the network mechanics of multi-user engineering and provides certified optimization strategies.

Architectural and System Mechanics

STEP 7 Database Architecture and Multi-User Network Dynamics:

File-Based Database Model: Unlike modern client-server relational databases, STEP 7 multiprojects consist of hundreds of indexed binary files (.dbf, .dbt, .s7p). Opening a single CFC chart triggers hundreds of individual file read/write lock requests across the network.
Network Latency Amplification: Over standard Windows SMB file shares, even a modest network latency (e.g., 5–10 ms ping) causes compounding delays. Every individual file lock negotiation halts the SIMATIC Manager UI thread.
Windows SMB Signing and Encryption: Windows Server security policies often enforce SMB signing and packet encryption. This adds cryptographic overhead to every database query, degrading multi-user throughput by up to 400%.
Multi-User Engineering Concepts:
Direct Multi-User Access: Multiple clients open charts within the same network-shared project. Only recommended on ultra-fast, low-latency LANs with under 1 ms latency.
Divide and Merge (Best Practice): Subprojects are removed from the central multiproject, edited locally on high-speed NVMe drives on client laptops/workstations, and merged back into the multiproject when completed.

Step-by-Step Engineering and Implementation Procedure

Step 1: Implement the Certified 'Divide and Merge' Workflow

For teams experiencing severe network lag, transition to the divide-and-merge approach:
1. On the Master ES, open SIMATIC Manager.
2. Right-click the subproject assigned to Engineer B -> 'Multiproject' -> 'Remove from Multiproject'.
3. Transfer the subproject folder (or archive zip) to Engineer B's local station drive C: or D:.
4. Engineer B performs all CFC, SFC, and hardware engineering locally with instantaneous sub-second response times.
5. Once engineering is complete, transfer the project back to the Master ES.
6. In SIMATIC Manager on the Master ES, select 'File' -> 'Multiproject' -> 'Insert into Multiproject' to rejoin the subproject.

Step 2: Optimize Network Infrastructure and Adapter Binding

If direct concurrent multi-user engineering is required:
1. Connect all ES clients to the Master ES via dedicated, wired Gigabit Ethernet switches (1 Gbps or 10 Gbps). Never engineer over Wi-Fi or high-latency VPNs.
2. Open Windows Explorer on each ES client, right-click Simatic Shell -> 'Settings'.
3. Confirm that the selected network adapter is strictly the dedicated engineering LAN adapter.

Step 3: Tune Windows SMB and File Sharing Settings

On the Master ES hosting the project share:
1. Open PowerShell as Administrator.
2. Inspect SMB signing status:
powershell Get-SmbServerConfiguration | Select-Object RequireSecuritySignature, EnableSecuritySignature
3. In an isolated, private engineering subnet, disable SMB signing to accelerate small-packet database file reads:
powershell Set-SmbServerConfiguration -RequireSecuritySignature $false -Force
4. Add the shared project folder to the antivirus exclusion list on all engineering stations.

Step 4: Reorganize the Multiproject Database

Have all engineers close their project connections.
On the Master ES, select 'File' -> 'Save As...'.
Check 'With reorganization (slow)' and click OK.
This cleans orphaned database pointers and compacts indexed tables, significantly reducing file lock contention.

Verification

To verify multi-user engineering performance:
1. On an ES client, open a complex CFC chart containing 50+ blocks; verify that the chart renders in under 3 to 5 seconds.
2. Test cross-chart navigation; confirm that jumping between interconnected blocks occurs smoothly without UI freezes.
3. Run a Delta Compile from an ES client; verify that compilation proceeds without database timeout warnings.

Limitations and Operational Precautions

Operational precautions:
- Disabling SMB signing should only be performed on isolated, physically secure OT engineering networks; do not disable SMB security on corporate enterprise networks.
- Two engineers must never attempt to modify the same individual CFC chart or HW Config station simultaneously; STEP 7 chart locking will reject concurrent writes to the same object.
- Always perform a full multiproject backup before executing 'Divide and Merge' operations.

Engineer FAQ

Q: Why is multi-user engineering so slow over standard Windows shares?

A: Because STEP 7 uses a legacy file-based database that issues hundreds of small synchronous file read/write locks per action, heavily penalizing network latency.

Q: What is the 'Divide and Merge' workflow?

A: A Siemens-recommended practice where subprojects are decoupled from the master multiproject, edited locally on client PCs, and re-inserted upon completion.

Q: Can engineers work over Wi-Fi?

A: No. Siemens strictly forbids engineering PCS 7 projects over Wi-Fi due to jitter, packet loss, and latency-induced database corruption.

Q: What network speed is recommended for multi-user engineering?

A: A minimum of 1 Gbps wired Ethernet with network ping times under 1 millisecond.

Q: What happens if two engineers open the same CFC chart?

A: The first engineer obtains write access; the second engineer receives a warning that the chart is opened in read-only mode.

Technical References

Related Tags

Multi-User Engineering, Multiproject, Divide and Merge, Network Latency, ES Client

Multi-User Engineering

20 respuestas

Optimizing Performance and Eliminating Network Delays in PCS 7 Multi-User Engineering