Fix SIMATIC NET Softbus Driver Preventing Windows Hibernation

When SIMATIC NET is installed on a Windows development workstation (typically a laptop used for PCS 7, WinCC, or STEP 7 engineering), the Softbus kernel driver and the SIMATIC NET Station Manager service register open handles and active Wait-style wait objects that prevent Windows from transitioning to Suspend-to-RAM (S3 standby) or Suspend-to-Disk (S4 hibernation). This article documents the root cause, the two field-proven workarounds (clearing the Station Configuration Editor and stopping the statmgr service), the verification procedure, and the operational caveats engineers must respect before resuming SIMATIC NET commissioning work.

1. Problem Description

Symptoms reported on engineering laptops running SIMATIC NET together with PCS 7 V6.x / V7.x or STEP 7 V5.x:

• Windows refuses to enter Standby or Hibernate after the lid is closed or after a timeout defined in the power scheme.
• The powercfg /requests command shows an active request from a SIMATIC NET module (commonly \Device\S7OPCSXA, \Device\SoftnetRT, or the S7DOS helper).
• After manually selecting Start > Shut Down > Standby, Windows returns to the active session within 2-3 seconds.
• The behavior is independent of any user application; it persists as long as the Station Configuration Editor (SCE) lists a non-trivial configuration.
• On Windows 7, the system tray reports "A program is preventing Windows from checking for power button presses"; on Windows 10/11 the equivalent message reads "Some drivers are preventing Windows from turning off the display or going to sleep".

The phenomenon is documented across the SIMATIC NET 6.x, 7.x, 8.x, and the SIMATIC NET PC Software 2008 / 12 product lines. It is not a defect in the strict sense - it is the expected behavior of a stack that owns kernel-level I/O. The engineering task is to make hibernation possible without corrupting the station configuration.

2. Affected SIMATIC NET Versions and Products

The table below summarises the PC software products and the components that participate in the standby/hibernate block. The official product matrix is published in the Siemens support entry referenced at the end of this section.

For a definitive list of which PC product requires which companion software, see the official Siemens support attachment: SIMATIC NET PC software product matrix (Siemens Support, ID 109478545).

3. Root Cause Analysis

Two separate mechanisms in SIMATIC NET prevent the operating system from entering low-power states:

3.1 Softbus Kernel Driver

The \Driver\Softbus driver (display name SIMATIC NET Softbus) is a kernel-mode, pseudo-bus driver that emulates a virtual backplane between the user-mode OPC server, the S7DOS helper, and any PC-CP (e.g. CP 1613, CP 1623) installed. As long as the Station Configuration Editor contains an index (a configured component) that is loaded, the Softbus driver keeps an open \Device handle that is registered with the Windows power manager. The power manager interprets this handle as a wake-blocking request.

The handle is released only when the SCE configuration is empty (i.e. only the Station Manager at index 125 remains) or when the entire SIMATIC NET stack is unloaded. This is the reason the laptop can enter standby or hibernation only after the SCE has been stripped of all loaded components.

3.2 Station Manager Service (statmgr)

The SIMATIC NET Station Manager is implemented as a Windows service named SIMATIC NET Station Manager (internal service key statmgr). The service periodically polls the SCE configuration and, while the workstation is configured, it holds a process-level power request equivalent to what the SetThreadExecutionState(ES_SYSTEM_REQUIRED) API imposes. This is what Microsoft describes in the Microsoft Q&A entry on standby mode and what is generally true for any driver that does not advertise PowerManagement capability in its IRP_MN_DEVICE_POWER_STATE handling.

Stopping the service removes the request and allows the OS to enter standby or hibernation immediately.

4. Preconditions Before Modifying the Configuration

1. Close all STEP 7, WinCC, PCS 7, S7-PCT, and SIMATIC NET Configuration tools.
2. Disconnect any S7 / PROFINET connection that is currently carrying live process data; saving the configuration is not sufficient, you must shut down the OPC server and S7DOS.
3. Export the existing SCE configuration: Station Configuration Editor > Station > Export. Save the .ncm file to a safe location; this is your rollback.
4. Confirm that no scheduled engineering task is in progress (e.g. download, online diagnostic, firmware update). These operations must not be interrupted by a service stop.
5. Open a command prompt as Administrator (cmd > Run as administrator) for all subsequent commands.

5. Solution 1 - Empty the Station Configuration Editor

This is the cleanest method and is the one Siemens support engineers recommend first.

1. Launch Station Configuration Editor (Start > SIMATIC > SIMATIC NET > Station Configuration Editor).
2. Select the index entry that represents your PC station (typically Index 1 for the first PC station, but can be any index < 125).
3. For each component (e.g. OPC Server, S7DOS, Application, CP 1613), right-click and choose Remove.
4. Leave Index 125 in place. Index 125 is reserved for the Station Manager and must not be removed; it is a non-blocking, lightweight component.
5. Click Station > Save and Compile. The SCE recompiles an empty station file.
6. Open a command prompt as Administrator and execute:

   net stop "SIMATIC NET Station Manager"
   net start "SIMATIC NET Station Manager"

   The restart forces the Softbus driver to release its current device handle and reload against the empty configuration.
7. Test the standby / hibernation behaviour. The system should now enter the low-power state within the configured timeout.

After waking, the SCE will still show only Index 125. To resume engineering work, re-import the previously exported .ncm file (see step 3 of the preconditions) and recompile the station.

6. Solution 2 - Stop the Station Manager Service

Use this method when the SCE configuration is required for the next working session and you need standby / hibernation only for a short, well-defined interval (e.g. overnight, or to transport the laptop).

6.1 Interactive stop

net stop statmgr

On success the service control manager reports:

The SIMATIC NET Station Manager service is stopping.
The SIMATIC NET Station Manager service was stopped successfully.

After this command the standby / hibernation request succeeds within 1-2 seconds. The handle to \Device\Softbus remains, but the service that registered the blocking IRP is gone, so the OS proceeds with the power transition.

6.2 Automated stop (batch file at logoff or scheduled task)

@echo off
net stop statmgr > nul 2>&
shutdown /h /t 0

Place the batch file in a location that is executed on logoff, or trigger it manually before closing the lid. The /h flag forces hibernation, the /t 0 sets the timeout to zero seconds.

6.3 Service startup mode change

To avoid manual stopping, change the Station Manager startup type to Manual:

sc config statmgr start= demand

Reverting to automatic startup is the same command with start= auto. The downside is that other SIMATIC NET tools (e.g. the OPC Scout) will not be able to find the station when they start; the service must be started on demand via net start statmgr.

7. Operational Considerations and Restart Procedure

Siemens documentation is explicit that the start-up and shut-down sequence of SIMATIC NET has to follow a defined order. A casual stop/start of the Station Manager can leave the Softbus driver in a half-loaded state, which is the most common cause of "Station not found" errors after a wake-up.

The recommended field-proven restart sequence is:

1. Stop Station Manager: net stop statmgr
2. Wait 10 seconds for the Softbus driver to release all handles.
3. Place the workstation in standby or hibernation.
4. Wake the workstation.
5. Reboot the workstation before resuming SIMATIC NET work. A cold boot re-initialises the Softbus driver, the SCE, and the OPC server in the correct order; a warm resume from S3/S4 has been observed to leave the station in a state where the OPC server cannot enumerate the configured components.

If the workstation is used only sporadically for SIMATIC NET, an alternative is to disable the Station Manager altogether (sc config statmgr start= disabled) and start it manually with net start statmgr only when needed.

8. Verification Procedure

After applying either solution, verify the fix with the following checks:

1. Open an elevated command prompt and run powercfg /requests. The output should show No active power requests or list only the Softbus handle without the [DRIVER] tag.

   DISPLAY:
   None
   
   SYSTEM:
   None
   
   AWAYMODE:
   None
   
   EXECUTION:
   None
   
   PERFBOOST:
   None
   

2. Run powercfg /energy for 60 seconds. The resulting energy-report.html should not list SIMATIC NET under Platform Power Management Capabilities or USB Suspend violations.
3. From the Windows Run dialog, type powercfg -hibernate on to confirm hibernation is enabled, then shutdown /h to force a hibernation cycle. The system must complete the cycle without returning to the active session.
4. Wake the system, log in, and verify that STEP 7, WinCC Explorer, or whichever tool you use, can still find the local PC station. If it cannot, perform the cold reboot described in section 7.
5. Re-apply the engineering configuration (re-import the .ncm file, recompile the station, restart the Station Manager) and repeat the test to confirm the issue is not a one-off.

9. Troubleshooting Matrix

10. Related Configuration and Advanced Settings

10.1 Disabling wake timers via Group Policy

On managed laptops, the group policy Computer Configuration > Administrative Templates > System > Power Management > Sleep settings can be set to Disabled for Specify a system wake policy. This complements the SIMATIC NET workaround by reducing competing wake requests from Windows Update or scheduled tasks.

10.2 PCI Express link state power management

When a CP 1613 / CP 1623 is present, set PCI Express > Link State Power Management to Moderate Power Savings in the power plan. Maximum Power Savings has been reported to cause PROFINET IO re-connection delays after a wake-up, especially with IRT.

10.3 Selective suspend for USB-C PROFIBUS / PROFINET adapters

For USB-attached PC adapters (e.g. Siemens PC Adapter USB A2), disable USB selective suspend in the power plan; otherwise the bus will be torn down before the Softbus driver can release its handle, producing a stop error 0x7E in Softbus.sys.

11. Frequently Asked Questions