Resolving PROFIBUS DP Slave GSD File Errors in Siemens STEP 7

When a third-party PROFIBUS DP slave such as a Bausch+Stroebel operator panel, a remote I/O block, a drives controller, or a process instrument is added to or replaced in a Siemens SIMATIC project, the engineering tool (STEP 7 V5.x HW Config or TIA Portal) must have the vendor's General Station Description (GSD) file loaded into its hardware catalog. If the GSD is missing, the slave station comes up with a configuration fault, the DP master reports the station as faulty, and the I/O cannot be exchanged. This article explains the root cause, the recovery path, and the field-proven procedure for sourcing and installing GSD files such as BT11_21.GSD on STEP 7 and TIA Portal, with verification steps and a fault matrix.

1. Problem Description

The classic symptom pattern reported in the field matches a missing or unreadable GSD:

• HW Config or TIA Portal reports "Unknown DP slave" or "Device not found in the hardware catalog."
• The DP slave icon shows a red question mark or red slash when the project is opened on a workstation that does not have the GSD installed.
• Downloading the hardware configuration to the CPU causes the affected station to go into bus fault (SF LED on, BF LED flashing at 1 Hz on the slave).
• The CPU diagnostic buffer logs entries such as "Station failure," "Diagnostic data not plausible," or "Configuration error" for the affected PROFIBUS address.
• With STEP 7 V5.x HW Config, opening the project on a PC that does not have the GSD installed strips the slave from the configuration, or refuses to save the project.

In one representative case, a machine tool with a Siemens S7-300 CPU and a Bausch+Stroebel KBA / KBB series operator panel (PROFIBUS DP slave, file BT11_21.GSD) could not be modified because the engineer did not have the original master project and could not obtain the GSD to keep the panel on the bus after a hardware download.

2. Root Cause Analysis

PROFIBUS DP is a vendor-agnostic fieldbus standardized in IEC 61158 / IEC 61784-1. To keep configuration tools vendor-neutral, the device description is shipped separately as a GSD file. The engineering tool cannot create a slave object on the bus without a GSD that matches the slave's PNO identity, baud rate, and I/O layout. The failure modes are well defined:

The GSD file (e.g. BT11_21.GSD) is a plain-text file that contains, in keyword form, the device's vendor name, model code, supported baud rates (9.6 kbps to 12 Mbps), maximum I/O bytes, slot count, diagnostic length, and module/parameter definitions. The associated bitmap file (BT11_21.BMP) is for the catalog icon only — it is not loaded into the PLC.

3. Sourcing the GSD File

Never fabricate or guess a GSD. The PNO identity number inside the GSD must match the identity broadcast by the physical slave during startup; mismatches produce a hard configuration fault. Use the channels below in order of preference.

3.1 Vendor / OEM support

For a Bausch+Stroebel KBA / KBB / KFA series operator panel, contact the original equipment manufacturer with the machine serial number and the panel part number. The OEM keeps the GSD, the Type 3 / Type 5 files, and the EDS on file with the device shipment and will email them on request.

• Bausch+Stroebel USA, 21 Commerce Drive, North Branford CT 06471 — phone 203-484-9933, toll free 866-512-2637, [email protected]
• Bausch+Stroebel Ilshofen (DE) HQ — +49-7904-701-0

Provide: machine serial number, panel model, the existing GSD filename (e.g. BT11_21.GSD), and the STEP 7 or TIA Portal version you are running. The OEM will normally return the latest GSD, the matching bitmap, and the parameter assignment sheet.

3.2 PROFIBUS GSD library (PI / profibus.com)

For devices listed by the PROFIBUS & PROFINET International (PI) organisation, the official GSD library is the authoritative source. The library is searchable by vendor name, product family, and PNO ID. Devices that ship with PI certification are listed at:

https://www.profibus.com/products/gsd-files

Download the GSD that matches the device's hardware revision. Where multiple GSDs are listed, select the highest Revision field that is still ≤ the device's firmware; installing a newer GSD than the device firmware supports is a common cause of "Prm data incorrect" faults at startup.

3.3 Siemens "Retrieve" / project archive

If the original STEP 7 project (.S7P) or a TIA Portal archive (.zap) is available, install the GSD by opening the project on the same engineering tool that originally created it. The catalog entries are stored inside the project, so Retrieve Project automatically re-installs the GSD into the local hardware catalog. This is the cleanest path when the original project exists.

3.4 Cross-vendor toolkits

Vendors such as ABB, SEW-Eurodrive, Siemens (for SIMATIC PDM), and Phoenix Contact publish device-specific GSD bundles. These are normally hosted on the vendor's support portal under Downloads → Software → GSD / GSDML.

4. Installing the GSD in STEP 7 V5.x (HW Config)

STEP 7 V5.4 / V5.5 / V5.6 use the SIMATIC Manager and HW Config. The GSD import path is unchanged across all V5.x releases.

Prerequisites

• Administrator rights on the engineering PC (the GSD is written under %ProgramFiles%\Siemens\Automation\SIMATIC Manager\S7HWCNF\).
• STEP 7 installed with the matching Service Pack (e.g. V5.5 + SP4 for SIMATIC Manager on Windows 7 / Server 2008 R2; V5.6 + SP1 for Windows 10).
• The GSD file and its .BMP bitmap extracted to a local folder (do not import from a network share — Windows file locking will fail the import on locked .BMP files).

Step-by-step

1. Close all open HW Config windows.
2. In SIMATIC Manager, choose Options → Install GSD File...
3. Browse to the folder containing BT11_21.GSD (and any companion .BMP or .DIB files).
4. Select the file. The File list column shows the device model and revision.
5. Click Install. Wait for the Installation completed dialog. The new device is registered in the HW Config catalog under PROFIBUS-DP → Additional Field Devices → <Vendor>.
6. Restart HW Config if the device does not immediately appear in the catalog tree (SIMATIC Manager caches the catalog for the active session).

Alternative: manual placement

For locked-down systems where the menu-driven install fails, copy the GSD, BMP and any companion files into the catalog directory of the active STEP 7 version and re-open HW Config:

Re-launch SIMATIC Manager; HW Config rebuilds the catalog by reading the directory on startup.

5. Installing the GSD in TIA Portal

TIA Portal V13 SP1 and later install PROFIBUS GSD files (file extension .GSD) and PROFINET GSDML files (extension .xml) through the Manage general station description files (GSD) dialog. The procedure is consistent from V15.1 through V20.

Prerequisites

• TIA Portal installed and licensed for the device family (TIA Basic for S7-1200, TIA Comfort for S7-1500 / ET200).
• The TIA Portal version ≥ the version that introduced the catalog family used by the device. Older TIA versions will reject GSD-V5 files written for newer device families.

Step-by-step

1. Open TIA Portal with the project (or a blank portal session).
2. Choose Options → Manage general station description files (GSD).
3. The dialog lists already-installed GSDs grouped by PROFINET (GSDML) and PROFIBUS (GSD). The Source path field is set to <TIA Portal install>\Data\HSP\....
4. Click Browse... and select the folder containing the vendor GSD (e.g. BT11_21.GSD).
5. Select the GSD row and click Install. The dialog reports the device family that the GSD will be merged into.
6. After the install completes, restart the TIA Portal Device & Networks editor — the new device appears under Catalog → Other field devices → PROFIBUS-DP → <Vendor>.

Official Siemens documentation for the procedure is published in the TIA Portal help: Install GSD file in TIA Portal V20. The same path applies to PROFINET GSDML installation in TIA Portal V13 through V20.

6. Re-Inserting the Slave into the Project

Once the GSD is installed, the existing project can be repaired.

1. Open the project in SIMATIC Manager (STEP 7 V5.x) or TIA Portal.
2. Open HW Config / Device & Networks.
3. Drag the slave from the catalog (now visible under the vendor folder) onto the PROFIBUS subnet at the correct DP address.
4. Open the slave object and re-assign the I/O slots that the original project used. If you have the original project's Object properties → Module list, use it verbatim; otherwise click Read from slave (DPV1) to read the real configuration from the device. Read from slave requires the slave to be online and addressable.
5. If you do not have the original slot layout and the slave is not online, open the vendor's parameter assignment sheet (the PDF the OEM supplies with the GSD) and rebuild the slot table by hand. Common defaults: 4 bytes of input at slot 1, 4 bytes of output at slot 2 for an HMI-type panel.
6. Save the project, then perform a Compile and check. Resolve any Type mismatch warnings before downloading to the CPU.

7. Verification

Verification is done in three layers — offline compilation, online diagnostics, and on-machine functional check.

7.1 Offline compile

• STEP 7 V5.x: Station → Save and Compile. No warnings should remain in the Compile Output window regarding the new slave.
• TIA Portal: Project tree → PLC → Compile → Hardware (rebuild all). The Messages pane must be free of Configuration error entries.

7.2 Online diagnostics on the CPU

1. Go online with the CPU (Online → Go Online in STEP 7 V5.x; Go online in TIA Portal).
2. Open the Diagnostics view of the DP master. In STEP 7: PLC → Module Information → Diagnostic Buffer. In TIA Portal: Online & Diagnostics → Diagnostics buffer.
3. Confirm the last diagnostic event is a "Station return" for the affected DP address, not a "Station failure."
4. Open the slave's Module Information → DP Slave Diagnostics. The Station status 1/2/3 bytes should read 0x00 0x00 0x00 (no fault) within a few seconds of bus start.
5. From the slave object properties, click Online → Monitor/Modify on the I/O area. Toggle a known output bit and confirm the physical action on the panel (LED, button feedback, screen change). For inputs, change a state on the panel and confirm the input bit flips in the monitor table.

7.3 Field functional check

• Power-cycle the DP segment, not just the CPU. Watch the BF LED on the slave — it should extinguish within 5 s at 1.5 Mbps, within 2 s at 12 Mbps.
• From the operator panel, initiate a function that requires PLC handshake (e.g. machine start, recipe load, count reset). Confirm cyclic I/O exchange is sustained for at least 10 minutes with no SF/BF flicker.

8. Troubleshooting Matrix

9. Field-Proven Caveats

• Bitmaps and the catalog icon: A missing .BMP does not affect runtime. The slave still functions, but the catalog shows a generic device icon and HW Config logs a "Bitmap not found" warning.
• GSD vs. GSDML: PROFIBUS DP devices use .GSD. PROFINET devices use .GSDML (an XML file with the GSDML-Vx.y- prefix). They are not interchangeable; the install dialog in TIA Portal sorts them automatically.
• DPV1 / DPV2: If the slave supports DPV1 (extended diagnostics, isochronous mode) and the GSD declares DPV1 slots, the master must run in DPV1 mode. S7-300 / S7-400 CPUs with firmware < V3.0 do not support DPV1 — upgrade the CPU firmware or fall back to DPV0 slots.
• Bus terminator power: The first and last devices on a PROFIBUS segment must have termination on, and only them. Leaving termination on a middle device collapses the signal and produces intermittent BF events that mimic a GSD problem.
• Bausch+Stroebel specifics: KBA / KBB series panels expose two PROFIBES variants — a DP slave (this article) and a DP master (MPI/DP switchable). Confirm the rotary address switches on the back of the panel before importing the GSD; a master-mode panel will not appear in the DP slave catalog at all.

10. Standards and Reference Documents

• PROFIBUS technology overview — PROFIBUS & PROFINET International (PI)
• PI Standard GSD Library (device catalogue)
• TIA Portal V20 — Install GSD file
• IEC 61158 / IEC 61784-1 — Industrial communications, fieldbus PROFIBUS DP profile
• PI GSD Specification v5.0 / v5.1 — keywords and slot definition

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