CP5611A2 Not Detected: PCI Installation Troubleshooting Guide

1. Problem Description

The Siemens CP5611A2 (order number 6GK1 561-1AA01) is a PCI communication processor used to connect a programming device (PG) or PC to SIMATIC S7/M7/C7 controllers over MPI, PROFIBUS, or PPI. The CP5611A2 is a 32-bit, 5 V PCI card that requires the SIMATIC NET PC software or STEP 7 to expose the card to applications.

The failure mode covered in this guide is the most common field complaint: the operator installs the CP5611A2 into a desktop PC, powers the system, logs in to Windows, and no new hardware notification appears, no balloon tip fires, and the card does not show up anywhere in Device Manager. The same card, moved to a different PC of the same vintage, installs and operates normally, confirming that the card itself is functional. This pattern points to a host-side incompatibility, not a card defect.

2. CP5611A2 Hardware Reference

The 5 V signaling requirement is the single most important specification. The CP5611A2 has the older "5 V keyed" PCI card edge (recessed toward the bracket side of the connector). It will only physically seat in slots that accept a 5 V card, which on most ATX boards means standard 32-bit PCI slots. Universal/3.3 V slots physically block the 5 V keying. Plug the card only into a slot whose rear contact strip is keyed for 5 V.

3. Root Cause Analysis

When the CP5611A2 fails to enumerate on a specific PC but works on a second PC, the root cause is one of the following host-side conditions, listed in order of statistical frequency:

1. Out-of-sequence driver installation. Windows has already booted with the card physically present, attempted to load a generic PCI bridge driver, and marked the device as failed. Subsequent install attempts of SIMATIC NET cannot overwrite a phantom device.
2. PCI slot signaling mismatch. The card is seated in a 3.3 V keyed or universal slot whose 3.3 V keying physically allows the card but the bus signals are referenced to 3.3 V. The card powers but does not enumerate.
3. BIOS PCI resource assignment. Plug & Play OS is set to "No" while an ACPI-aware OS is loaded, leaving the card without an IRQ/IO window.
4. IRQ sharing conflict with a legacy onboard device (IDE, USB 1.1, AC97 audio) that the BIOS refuses to resolve.
5. Defective or marginal PCI slot (bent pin, oxidized contact) on the failing motherboard.
6. Reserved memory hole (E000 segment) that hides the card's option ROM.

The official Siemens troubleshooting entry point is documented in the Siemens Industry Online Support article "What can you do if the CP5611 cannot be installed or commissioned?". The first action Siemens recommends is to open Device Manager (Control Panel → System → Hardware tab → Device Manager) and observe whether the card appears as an unknown PCI device.

4. Pre-Diagnostic Checklist

Before changing any hardware, gather the following information:

5. Step-by-Step Resolution

5.1 Establish the failing baseline

1. Power down the host. Disconnect mains.
2. Confirm the CP5611A2 is fully seated in a 32-bit 5 V keyed PCI slot (white plastic, recessed toward the rear of the case). Reseat the card firmly.
3. Power on. Watch the POST screen for a PCI device listing. The card should appear as a PCI device with a vendor ID of 0x110A (Siemens AG) and device ID 0x4036 (CP5611A2).
4. Log in. Open Device Manager (Start → Run → devmgmt.msc).

5.2 Test every PCI slot

Move the card to each available 32-bit PCI slot, one at a time, rebooting after each move. On the HP Compaq dx2300 (Intel 945G Express chipset, ICH7), the typical layout provides two or three PCI slots behind a riser or directly on the board. Test each in turn. The dx2300 uses standard 5 V keyed slots; the card should physically fit. If it fits electrically but does not enumerate in one slot and enumerates in another, the failing slot is defective and should be retired.

5.3 Force a device rescan

1. Open Device Manager.
2. Action menu → Scan for hardware changes.
3. Observe whether a new entry appears under "Other devices" with a yellow question mark. If yes, right-click → Update Driver → point to the SIMATIC NET CD driver path (typically D:\Siemens\SIMATIC.NET\CP5611\ or C:\Program Files\Siemens\SIMATIC.NET\Drivers\CP5611).

If the card does not appear at all even after rescan, Windows cannot see it. Move to Section 5.4.

5.4 Install SIMATIC NET/STEP 7 first, then the card

This is the canonical fix for the symptom described in the source report:

1. Power down and remove the CP5611A2.
2. Insert the SIMATIC NET PC Software CD (or STEP 7 V5.x CD). The CP5611 driver is bundled with both.
3. Run Setup.exe. Accept defaults. A reboot will be required at the end of the install.
4. After the reboot, power down again and insert the CP5611A2 into a 5 V PCI slot.
5. Power on. The Plug & Play wizard should now detect "Siemens CP 5611 A2" and complete driver installation automatically.
6. Open Set PG/PC Interface (Start → SIMATIC → STEP 7 → Set PG/PC Interface) and confirm the CP5611A2 appears as an assignable interface.

5.5 BIOS adjustments for the dx2300

On the HP Compaq dx2300, enter BIOS with F10 at POST. Verify:

Save and exit. The system reboots. After Windows loads, repeat the Device Manager scan from 5.3.

5.6 Manual driver load from INF

If the device appears as "Unknown PCI Device" in Device Manager:

1. Right-click → Update Driver.
2. Choose "Install from a list or specific location (Advanced)".
3. Choose "Don't search. I will choose the driver to install".
4. Click Have Disk and point to CP5611A2.INF on the SIMATIC NET CD (path: ...\Driver\CP5611\WinXP\CP5611A2.INF).
5. Confirm the driver signature prompt. The CP5611A2 driver is signed by Siemens AG.
6. Reboot when prompted.

5.7 Clear a phantom device entry

If the card previously enumerated and was removed without uninstall, Windows retains a hidden device entry. On XP:

1. Set the DEVMGR_SHOW_NONPRESENT_DEVICES environment variable to 1.
2. Open Device Manager → View → Show hidden devices.
3. Locate the greyed-out CP5611A2 under "SIMATIC NET" or "Other devices".
4. Right-click → Uninstall.
5. Power down, re-seat the card, power on, and let Plug & Play redetect.

5.8 Replace the slot or the riser

On the dx2300, the PCI slots sit on a riser in some chassis configurations. A bent riser pin or cold solder joint on the riser can pass continuity to DVM but fail under the 5 V inrush the CP5611A2 draws. Reseat the riser. If enumeration still fails across multiple risers, the motherboard's PCI bus is suspect.

6. Verification

After any of the fixes above, verify the card is fully operational:

1. Device Manager → SIMATIC NET → CP 5611 A2 → Properties shows "This device is working properly" and a populated PCI bus number, device number, and function.
2. Open Set PG/PC Interface (STEP 7). The CP5611A2 appears in the interface list. Select it and click Diagnostics.
3. In the Diagnostics window, click Test. The card reports its bus address, firmware version, and PROFIBUS node address (default 0). The status should be "OK".
4. Connect the card to a live MPI/PROFIBUS segment and click Read in Diagnostics. Active nodes populate the list within a few seconds.
5. From SIMATIC Manager → Options → Set PG/PC Interface, run Node Test against an S7-300 / S7-400 CPU on the bus. A successful read of the CPU's online identification confirms the full driver/MPI/PROFIBUS stack.

7. dx2300-Specific Quirks

The HP Compaq dx2300 is a 2006-vintage business desktop built around the Intel 945G Express + ICH7. Several field-reported quirks are worth noting:

• BIOS revisions below 1.09 mishandle PCI IRQs above IRQ 16, which can prevent enumeration of add-in PCI cards when USB controllers claim low IRQs. Update the BIOS to the latest revision available on the HP support site for the dx2300.
• Default MPS table in early dx2300 BIOS revisions is 1.1, which is incompatible with some Siemens PCI drivers. Force 1.4 in BIOS (see 5.5).
• Device Security in the dx2300 BIOS can disable individual PCI slots; the symptom is identical to a defective slot. Verify that the target slot is not administratively disabled.
• Windows XP SP2 5 V PCI power pin: Some 945G boards deliver a marginally regulated 5 V rail to PCI. The CP5611A2 draws up to 400 mA. An under-spec PSU can drop the rail under load and the card silently de-enumerates. Test with a known-good 300 W PSU.

8. Diagnostic Matrix

9. When the Card Still Refuses to Enumerate

If the CP5611A2 refuses to enumerate after exhausting all of the above, escalate in this order:

1. Test the card in the second, known-good PC that previously worked. Confirm it still works. This re-establishes the card's baseline.
2. Test a different known-good CP5611A2 in the failing PC. If a second card also fails, the host is the problem, not the card.
3. Test the card in a third, modern PC with a current OS. If it works, the failing PC has a host issue.
4. If the card is needed on a modern Windows host where the original CP5611A2 driver no longer installs, migrate to a CP5611A3 (6GK1 561-1AA02) or to a CP5711 USB adapter, both of which have current 64-bit Windows 10/11 driver support. The CP5711 is the recommended replacement for new installations on hardware lacking a 5 V PCI slot.
5. Capture a complete msinfo32 report and a Device Manager export and open a support request against the Siemens KB article referenced in Section 3, attaching the report.

10. Field-Proven Tips

• Always install SIMATIC NET/STEP 7 before physically inserting the CP5611A2 on a fresh host. This is the most common cause of the exact symptom described in the source report.
• Keep a bootable USB stick with a known-good XP image containing SIMATIC NET preinstalled. This turns the dx2300 from a 30-minute debug into a 5-minute swap.
• Mark each 5 V PCI slot on a label affixed inside the case. Universal slots are not CP5611A2 compatible for some Siemens card revisions.
• If a CP5611A2 fails after a BIOS update, reflash to the previous revision; the dx2300 BIOS has been known to break PCI enumeration in point releases.
• For long-term support, retire any PC running Windows XP SP2. Microsoft ended XP support in 2014 and modern Siemens automation software is moving to 64-bit Windows 10/11. The CP5711 USB adapter (6GK1 571-1AA00) is the forward-compatible migration path and does not depend on PCI slot signaling at all. For further context on modern Windows releases, consult Microsoft's Windows 11 23H2 release health page for resolved driver issues that may also affect modern Siemens PC adapters.