Resolving STEP 7 V5.6 Trial License Activation for S7-300 CPUs

When a maintenance engineer needs to come online with a legacy SIMATIC S7-300 controller for the first time, the very first obstacle is rarely the field wiring or the program logic. It is the licensing subsystem of STEP 7 Professional (V5.6 / V5.7). This reference documents a field-proven procedure to obtain, install, and verify a 21-day trial license, identify the affected hardware, recover program data from a Siemens MMC, and choose the correct PC adapter to bring the controller online.

1. Problem Definition

Typical first-use failure modes when commissioning STEP 7 on a Windows 10/11 engineering workstation:

• SIMATIC Manager opens an error dialog stating the license key could not be found and the application will close, but the dialog is modal and blocks the splash screen, hiding the Activate Trial License button.
• Automation License Manager (ALM) is not present in Start → Siemens Automation → Automation License Manager after installation, so the trial cannot be moved to the local license container.
• The installer refuses to launch on a recent Windows build unless a registry key is added, which Siemens support documents as required and which voids the standard warranty.
• Windows 10 prompts to format the MMC (Micro Memory Card) pulled from the CPU because it is not a FAT/FAT32 SD card and is treated as raw media.
• An attempt to connect the CPU over a generic USB→RS232 adapter fails because the S7-300 front ports are MPI/Profibus, not RS-232.

Each of these symptoms traces back to a single root cause group: the engineer has the engineering software installed but has not yet bound a license to the local PC, and the auxiliary tools (ALM, MMC reader, MPI cable) needed to actually use it are not in scope of the standard install.

2. Affected Hardware Identification

Always confirm the part numbers of the target controller before purchasing cabling, MMC readers, or migration tools. The article's reference platform uses the following components:

For the ET 200S, verify firmware with the part number suffix. The 8AB01-0AB0 supports PROFINET IO controller mode and is fully addressable from STEP 7 V5.4 SP5 and later, and from TIA Portal V13 SP1 and later.

3. STEP 7 V5.x Trial License Acquisition

Siemens publishes two distinct trial packages, and the choice depends on the version of the engineering tool you are testing:

3.1 Choosing between V5.6 SP2 and V5.7 SP2

STEP 7 V5.6 SP2 is the last V5.x release with broad S7-300/400 support and is the recommended target when the cabinet contains legacy CPU 6ES7 313/314/315/316, ET 200S, or ET 200M stations. STEP 7 V5.7 SP2 adds Windows 10 LTSC 2021 and Windows 11 support, but the same hardware catalog is supported. For mixed fleets where the S7-300 will eventually be migrated, install V5.6 SP2 today and reserve TIA Portal V18 or V20 for the migration project.

4. Installation Pre-checks

4.1 Administrator rights and user account control

STEP 7 V5.x must be installed by a local administrator. The installer writes protected registry keys under HKLM\SOFTWARE\Siemens\Automation and places services such as S7Trace and ALM Service into %ProgramFiles%\Siemens\Automation.

4.2 Operating system compatibility

STEP 7 V5.6 SP2 supports Windows 7 SP1, Windows 10 (1607 and later up to 21H2), and Windows Server 2016/2019. STEP 7 V5.7 SP2 adds Windows 10 22H2, Windows 11 21H2/22H2, and Windows Server 2022. Windows 11 24H2 is supported only by the V5.7 SP2 hotfix, which is delivered through SIOS entry 109820861.

4.3 The registry key that lets the installer run

On a clean Windows 10/11 box the STEP 5/7 setup wrapper sometimes blocks the launch with a Microsoft .NET Framework 4.x prerequisite error even when the runtime is present. Siemens support documents the following workaround, which the engineer must apply manually:

1. Open regedit as administrator.
2. Navigate to HKLM\SOFTWARE\WOW6432Node\Microsoft\.NETFramework.
3. Create DWORD value OnlyUseLatestCLR = 1.
4. Reboot, then re-launch the STEP 7 setup.

4.4 Microsoft Visual C++ and message queueing

SIMATIC Manager and ALM rely on MSMQ (Microsoft Message Queuing) for inter-process license traffic. Add the Windows feature Message Queuing → Message Queuing Server before installing, otherwise ALM service registration fails silently and the trial license cannot be moved to the local license container.

5. Activating the 21-Day Trial License

Once STEP 7 V5.6 SP2 (or V5.7 SP2) is installed, perform the trial activation. The procedure below resolves the symptom of the error dialog blocking the splash screen.

5.1 Standard activation sequence

1. Close every Siemens process from the taskbar (SIMATIC Manager, ALM, S7-PCT).
2. Launch Automation License Manager from the Start menu. The path is typically Start → Siemens Automation → Automation License Manager.
3. In the ALM left tree, confirm that the local license container (the disk icon) is selected. The container is the PC's own hard drive; remote containers correspond to network license servers (not used for the trial).
4. Right-click the empty right-hand pane and choose Activate Trial License → STEP 7 Professional.
5. ALM will reach the Siemens License Server over HTTPS, validate the SIOS account, and return a 21-day license to the local container.
6. Confirm the row STEP 7 Professional; 21-day trial; expires on <date> now appears in the container.
7. Launch SIMATIC Manager. The license error dialog is replaced by the normal project view.

5.2 Recovery when ALM is missing

If ALM was not installed, the trial-license entry never appears in Start → Siemens Automation. The cause is a non-admin install or a setup that was interrupted after the ALM service registration. Reinstall using Setup → Modify → Automation License Manager and confirm that the ALM Service exists under services.msc with start type Automatic.

5.3 Recovery when the error dialog blocks the splash

This is the most reported first-use defect. The License not found dialog is owned by SIMATIC Manager and is always-on-top, which prevents the engineer from clicking the Activate button on the splash screen. Use the recovery path:

1. Open ALM first (it is its own process, not owned by SIMATIC Manager).
2. Activate the trial license as described in section 5.1.
3. Close SIMATIC Manager by ending S7WEBSVC.exe and simaticmgr.exe from Task Manager.
4. Re-launch SIMATIC Manager. The license is now in the local container and the dialog will not appear.

6. Bringing the S7-300 Online

6.1 Port map of the CPU 6ES7 313-6CF03-0AB0

For commissioning, the USB-to-MPI/Profibus cable referenced in the field notes is the Siemens PC Adapter USB A2 with order number 6GK1571-0BA00-0AA0. It supports MPI at 19.2/187.5 kbit/s, PROFIBUS DP at 9.6 kbit/s to 1.5 Mbit/s, and PPI for S7-200. Note: the 1.5 Mbit/s DP ceiling is hardware-limited. If the existing PROFIBUS segment is configured for 3, 6, or 12 Mbit/s, you must use the PROFIBUS port on a CP (for example, CP 342-5) or a PROFIBUS PC card that supports the higher bus speed.

6.2 Selecting the PG/PC interface

In SIMATIC Manager, choose Options → Set PG/PC Interface and select the access point S7ONLINE (STEP 7) → PC Adapter (MPI) or PC Adapter (PROFIBUS). The dropdown maps the USB cable to the appropriate protocol layer. Always confirm the bus parameters match the live PROFIBUS segment; the default 1.5 Mbit/s is incompatible with a 12 Mbit/s segment and will produce bus-fault diagnostics on the DP slaves.

6.3 Online connection procedure

1. Connect the USB cable to the PC and the MPI/DP port of the CPU.
2. Right-click the S7-300 station in the SIMATIC Manager project tree and choose Target system → Display → Accessible nodes.
3. SIMATIC Manager scans the bus. The CPU appears with its MPI or PROFIBUS address and firmware version.
4. Right-click the detected node and choose Upload Station to PG to bring the on-line program into the project tree.

7. MMC Card Handling and Program Recovery

The Micro Memory Card in an S7-300 is a proprietary Siemens memory module. It is not an SD card. Inserting it into a standard SD reader on Windows 10 produces the "You need to format this disk" prompt. Never accept the format prompt: Windows would overwrite the card with a FAT volume and destroy the Siemens file system, including the active project.

7.1 Recovering the program from the MMC

There are two supported paths to read the program off the MMC without booting STEP 7:

1. External MMC reader (Siemens Field PG or USB MMC reader): The Siemens Field PG M5 Premium and its variants include an integrated MMC slot that exposes the Siemens file system to STEP 7. After installing STEP 7 and connecting the reader, the MMC appears under My Computer as a removable drive with the S7_DAT layout. Use SIMATIC Manager → PLC → Download User Program to Memory Card to view the contents.
2. Binary inspection: A binary editor such as HxD can read the raw blocks. Each block (OB, FB, FC, DB) is stored as a header-tagged record. This is useful for forensics and for extracting DB initial values, but the resulting code is the compiled Statement List (STL) rather than LAD or FBD.

7.2 MMC part numbers and capacity

8. Uploading a Program: STL Versus LAD/FBD

An upload from an S7-300 CPU returns the program block by block, exactly as it is stored on the device. If the original programmer wrote in Ladder (LAD) or Function Block Diagram (FBD), the on-line block is still the compiled STL. STEP 7 will display the block in whichever view the source language is closest to, but switching between views can be lossy.

• STL → LAD: Most STL constructs can be converted back to LAD, but complex bit/word operations, accumulator math, and indirect addressing remain in STL.
• STL → FBD: Boolean STL converts cleanly; arithmetic does not.
• Tag names and comments: Symbolic names and network comments are stored in the offline project, not on the CPU. An upload yields Absolute addressing only (I5.1, MW20, DB10.DBD4). The placeholder names TAG1, TAG2, TAG3 are STEP 7's auto-generated symbols when no symbol table exists.

9. TIA Portal Migration Path

The two controllers in the reference cabinet are both supported by TIA Portal V18 and later, including the ET 200S IM 151-8 PN/DP (6ES7 151-8AB01-0AB0). The decision to migrate is a separate question from the licensing question, but it affects the choice of trial.

For the immediate fix-the-issue scenario, stay on STEP 7 V5.6 SP2. Plan the TIA Portal migration as a separate, well-scope project, with a STEP 7 → TIA Portal migration tool run from inside TIA Portal Portal → Migrate project.

10. Verification Checklist

Run the following checks to confirm the install is healthy before touching the live program:

1. Open SIMATIC Manager → Help → About. The splash lists STEP 7 Professional V5.6 SP2 with no license warnings.
2. In ALM, verify the trial row reads Expires: <date 21 days from activation>.
3. Plug the PC Adapter USB into the CPU MPI port. The ACTIVE LED on the CPU transitions from solid to blink at the configured baud rate.
4. Open Accessible nodes; the CPU appears with correct MPI address (default 2).
5. Upload the station. Block list (OB1, OB35, FB/FC count) matches the documentation.
6. Open OB1 in LAD view. If LAD is greyed out, the original code was STL; the upload is still valid.
7. Insert the MMC back into the CPU and perform a Download to Target Device from the modified project. Wait for the Download successful dialog.
8. Watch the CPU diagnostic buffer (PLC → Diagnostic/Setting → Diagnostic Buffer) for SF/BF faults after restart.

11. Troubleshooting Matrix

12. Frequently Asked Questions