Installing PC Adapter USB A2 Driver for STEP 7 and TIA Portal

1. Product Identification and Scope

The Siemens PC Adapter USB A2 (Siemens part number 6GK1571-0BA00-0AA0, sometimes printed in older datasheets as 6GK1-571-0BA00-0AA0) is a USB-to-MPI/PROFIBUS/PPI programming interface used with SIMATIC S7-200, S7-300, and S7-400 programmable logic controllers. It converts between USB 1.1/2.0 on the engineering workstation and the RS-485 differential physical layer used by Siemens MPI and PROFIBUS DP networks at bus speeds from 9.6 kbps through 12 Mbps.

The adapter ships with a 3 m RS-485 PROFIBUS cable terminated in a Siemens 9-pin sub-D male connector. Power is drawn from the USB bus; no external supply is required. Galvanic isolation between the USB side and the MPI/PROFIBUS side is supplied on board.

Two driver installation paths must be understood before commissioning:

1. STEP 7 V5.5 and later, and TIA Portal V13 and later — drivers ship inside the engineering software installer as part of the SIMATIC Device Drivers bundle. The original CD shipped with early A2 units is therefore no longer required.
2. Legacy Windows XP or Windows 7 32-bit hosts without the matching SIMATIC DVD present — a separate driver package referenced by Siemens Support Entry ID 109476315 must be applied.

1.1 Catalog identification matrix

2. Hardware and Electrical Specifications

3. Supported Operating Systems

Compatibility is dictated entirely by the SIMATIC software, not by the adapter hardware. Use the table below to short-list the supported combinations before installing any driver. Where Siemens releases a new compatibility statement, treat that as the binding source over third-party blogs.

4. Driver Installation — Standard Path (STEP 7 V5.5 and TIA Portal)

For all currently released SIMATIC packages, do not attempt to install drivers from the A2 CD. The driver is delivered as part of the SIMATIC Device Drivers package automatically staged during the engineering software install.

4.1 Procedure

1. Insert the SIMATIC DVD (STEP 7 V5.5 or TIA Portal) or mount the ISO.
2. Run the setup as an administrator. The installer stages the missing adapter driver under the SIMATIC Device Drivers directory.
3. When setup completes, connect the A2 to a free USB port. Windows Plug & Play matches the device to the staged driver automatically. A power-cycle of the adapter (unplug/replug) may force the enumerator to detect the hardware if it was attached first.
4. Open Start → Programs → Siemens Automation → Set PG/PC Interface and confirm PC Adapter (Auto) or PC Adapter (MPI) appears in the Interface Assignment list.
5. To verify, start STEP 7 Manager; choose PLC → Accessible Nodes. The adapter and the connected PLC should both appear.

4.2 Files staged by SIMATIC Device Drivers

5. Driver Installation — TIA Portal Path

For TIA Portal V16 and later the driver may arrive as a Support Package rather than auto-install. Wire it as follows.

1. Start TIA Portal. Close the active project before changing drivers.
2. Open Options → Support Packages → Install Support Package.
3. Browse to the support package that ships on the TIA Portal install media (folder typically named Support) and select the PC Adapter USB A2 entry.
4. Restart TIA Portal.
5. Wire Online → Accessible Devices → Interface: PC Adapter USB A2 and run a refresh.

6. Driver Installation — Legacy Windows XP or Windows 7 32-bit (Without SIMATIC DVD Present)

If the engineering workstation is rebuilt as a clean Windows XP SP3 or Windows 7 32-bit host and no SIMATIC installer is available, the separate driver setup documented by Siemens Support Entry ID 109476315 must be applied.

6.1 Obtaining the driver setup

1. Open Siemens Industry Online Support entry 109476315 and download the attached driver package.
2. Extract the archive to a known path, e.g. C:\Siemens\A2\.
3. On a Windows 7 64-bit host, set the group policy to allow third-party unsigned drivers, or restart the host in F8 driver-signing-disabled mode.

6.2 Installation steps

1. Plug the A2 into a USB port.
2. When Windows detects new hardware, point the wizard to the extracted C:\Siemens\A2\ folder.
3. Allow several seconds for the unsigned-driver prompt. Accept with Install this driver software anyway.
4. Confirm Siemens PC Adapter USB A2 now appears under Device Manager → Universal Serial Bus controllers. The device must show Device is working properly with no Code 39 or Code 28.

7. Recovering the Original CD Image

When no internet access is permitted or the engineering PC is offline (audit-only site), recover the CD image as follows:

1. Locate the original A2 packaging. The CD is labelled SIMATIC PC Adapter USB A2 Driver and Documentation with MLFB 6GK1571-0BA00-0AA0.
2. If the CD is lost, request a duplicate from Siemens Industry Online Support under ticket category CS – SIMATIC Distributed I/O – Programming Tools, quoting the MLFB.
3. Mount the ISO (Windows 8/10/11): right-click disc image → Mount. For older hosts, install any virtual-CD driver.
4. Run the setup program from the root of the mounted image. The installer registers the USB kernel driver.

8. Set PG/PC Interface Configuration

Drivers installed silently do not always update the PG/PC Interface selection. Confirm the access point is bound to the A2.

1. Open Set PG/PC Interface from the Start menu (or run s7opcwcfg.exe for OPC-tag-bound configurations).
2. Tab Access Point of the Application; locate S7ONLINE and assign PC Adapter (Auto).
3. Tab PC Adapter / MPI / PROFIBUS (Auto); set the MPI address of the PC to 0, the highest station address to 31, and leave the transmission rate default of 187.5 kbps to match a default PLC MPI bus.
4. Click Diagnostics and run Test on the active MPI bus. The expected response is "OK – All stations listed" with the connected PLC visible at MPI address 2 by default.

9. Troubleshooting Matrix

10. Verification

Validate the driver installation by completing each step in sequence. Any failure identifies the specific layer (OS / driver / application / bus) that is misconfigured.

1. Device enumeration: open Device Manager and confirm Siemens PC Adapter USB A2 is listed without warning indicators.
2. PG/PC interface: confirm PC Adapter (Auto) is bound to S7ONLINE.
3. Accessible nodes: from STEP 7 V5.5, run PLC → Accessible Nodes; from TIA Portal, run Online → Accessible Devices. The local USB adapter and the connected PLC must both appear.
4. Online diagnose: open the target PLC project and execute PLC → Online → Diagnostic Buffer. The diagnostic buffer must load over the bus.
5. Block upload/download: upload a known block from the PLC or download a test block to confirm bidirectional traffic.

11. Replacement and Successor Hardware

If the original A2 cannot be brought back to operation, the following alternatives meet identical use cases.

12. Field-Engineer Notes

• The driver is unsigned on Windows 7 64-bit hosts and below; install with the anti-signing override. On Windows 10 64-bit and later the driver is signed by Siemens.
• Always confirm USB Root Hub power management is unlocked before mobile commissioning. Many intermittent "device dropped offline" reports disappear immediately when selective suspend is cleared.
• Use USB cable length ≤ 3 m. Extension cables break the USB high-power envelope and degrade isolation resistance.
• When reusing an A2 between projects, run Set PG/PC Interface → Diagnostics → Test before connecting to the live PLC. Substituting the wrong bus profile silently stores alternative maximum station addresses that corrupt larger MPI/PROFIBUS layouts.
• When bringing an A2 from a non-industrial environment, perform an ESD wipe by touching the host chassis before insertion. The adapter housing is not electrically grounded when used on a plastic-laptop chassis.
• After a Windows major update (e.g., 22H2 → 23H2) revisit Device Manager. Some cumulative updates temporarily revoke unsigned-driver associations and re-apply even when the driver itself is unchanged.

Frequently Asked Questions