PROFIBUS GSD File Installation in STEP 7 5.5 HWConfig Guide

Overview of PROFIBUS GSD Files

A GSD file (General Station Description) is the standardised, vendor-supplied ASCII text file that integrates a third-party PROFIBUS DP slave into a SIMATIC STEP 7 project. The format, the keyword grammar, and the required entries are specified by PI (PROFIBUS & PROFINET International) and form the contract between any DP master configuration tool and any DP slave regardless of manufacturer.

The PROFIBUS GSD specification is publicly available from PI - GSD Specification. Companion downloads and the searchable GSD library across all registered devices are listed at PI - Standard GSD Libraries. Across both files, system integrators determine:

• Vendor name, model name, hardware/firmware revision and the unique Ident Number (assigned by the PNO test lab).
• Supported baud rates (9.6 kbps up to 12 Mbps) and the currently active baud rate.
• DP version supported (DPV0, DPV1, DPV2 class-1 / class-2 services).
• Maximum diagnostic length, max module count, max channel count per module.
• Number, direction (input/output), consistency width, and unit (bit / byte / word) of every slot the slave offers.
• Available text strings for module descriptions and diagnostic messages.

For drives such as the Vacon NX family fitted with an OPTC3 or OPTC5 PROFIBUS option board, the GSD file is normally supplied together with the board manual (Vacon-NX-OPTC3-C5 Profibus Board User Manual) and is keyed to the option firmware revision. Always re-confirm the file revision matches the hardware before commissioning, otherwise HWConfig will reject the file with an "Ident number inconsistent" alarm or fall back to a generic slot.

Prerequisites and Required Toolchain

Locating and Validating the Vendor GSD File

Open the vendor GSD file in any text editor. The header block is fixed by the GSD specification and looks similar to the following excerpt:

\ Profibus_DP
GSD_Revision = 2
Vendor_Name  = "Vacon"
Model_Name   = "VACON NX OPTC3"
Revision     = "FW 1.20"
Ident_Number = 0x09A2
Protocol_Ident = 0
Station_Type = 0
FMS_supp     = 0
Hardware_Release = "1.0"
Software_Release = "V1.20"
9.6_supp = 1 ; 19.2_supp = 1 ; ... ; 12M_supp = 1
... 

Module = "PPO Type 3 (0 PKW, 2 PZD)" 0x0F, 0x05
EndModule

Validate the file before importing it. The check sequence in the field:

1. Compare the printed Ident_Number against the value shown on the option-board label or in the board manual.
2. Confirm supported baud rates include the master line speed (DP-1 is normally left at the auto-detect master behaviour; explicit Set_Slave_Add_supp = 1 is required if the drive is addressed by software address > 126).
3. Inspect the Max_Diag_Data_Len and the maximum user data length.
4. Confirm consistency types used by each module: 0x00 = byte, 0x01 = word, 0x04 = total-module consistent (use this for process data that must not split between PLC scan cycles).
5. Check the bitmaps exist: VACON_NX.bmp must accompany the .gsd. STEP 7 uses these BMPs in the catalog tree.

Installing the GSD File in STEP 7 HWConfig

1. Launch SIMATIC Manager. Open the target S7-300 / S7-400 project (or create a new one with a CPU 31x-2 DP).
2. Click on the SIMATIC 300 Station / SIMATIC 400 Station container and double-click Hardware to launch HW Config.
3. From the HW Config menu select Options → Install GSD File....
4. In the dialog, browse to the folder containing the .gsd (and optional .gsg, .bmp) files. Set the filter to GSD file (*.gsd). Multiple files can be highlighted and installed in one batch.
5. Click Install. STEP 7 parses each file, runs the GSD tokenizer, and copies the files into <STEP7 path>\S7DATA\GSD\. The catalog is rebuilt; wait for the progress bar to complete.
6. Close and re-open HW Config so the new device appears in the catalog tree.

Adding the Slave to the PROFIBUS DP Network

1. In HW Config, select the DP master (the CPU rail with the DP interface or an external CP). The PROFIBUS subnet object appears below the master.
2. Right-click the PROFIBUS (1) : DP master system slot and choose Add Master System if none exists, or simply Properties... to set bus parameters (transmission rate, profile, highest station address / HSA).
3. Open the hardware catalog on the right side of HW Config. Navigate to PROFIBUS DP → Additional Field Devices → Drives → <Vendor Name>. The newly imported device appears as a subfolder; for Vacon this resolves to Vacon Drives → VACON NX OPTC3.
4. Drag the slave icon from the catalog into the PROFIBUS line. The dialog Properties - PROFIBUS Interface OPTC3 opens.
5. Assign a unique PROFIBUS address (1 - 125). The HSA must be equal to or greater than this address, otherwise the master will not poll the slave.
6. Confirm "Watchdog" is enabled (recommended for drives), and leave the diagnostic address at the default unless you are using a custom diagnostic FB.

Selecting the PPO Telegram and I/O Byte Mapping

DPV0 PROFIdrive slaves negotiate process data via predefined PPO (Parameter / Process Data Object) telegrams. Pick the telegram type from the slot 1 configuration of the slave in HW Config; this simultaneously sets the byte count, consistency, and the I address / Q address ranges reserved in the CPU.

Place the appropriate PPO module into slot 1 of the slave; remove any redundant modules from slots 2 / 3. Confirm the consistency type is shown as "Total length" for the PZD area. When you re-enter the slot, STEP 7 will preallocate I/O address ranges, for example:

Input  Word   256..263   (12 bytes for PPO1 = 6 words)
Output Word   256..263

These addresses are then moved into the IEC process image with SFC26/SFC27 (update process image partitions) or read directly with L PIW 256 / written with T PQW 256. For PPO consistency, prefer SFC14 / SFC15:

CALL  SFC 14  // DPRD_DAT
LADDR  := W#16#100                  // PPO1 input, base PIW256
RET_VAL := MW 100
RECORD  := P#DB100.DBX0.0 BYTE 12   // 6 words packed into DB100

CALL  SFC 15  // DPWR_DAT
LADDR  := W#16#100
RECORD  := P#DB101.DBX0.0 BYTE 12
RET_VAL := MW 102

Configuration Notes for Variable-Speed Drives

After the slot is selected, set the drive-side parameters that mirror the master slot choice:

• Vacon NX OPTC3/C5: parameter P17.1 selects the active telegram; always set the value through the panel or Drive Tool before commissioning to ensure consistency between the GSD-selected PPO and the option-board side.
• PKW channel: if parameter access is not required, select PPO 3 or PPO 4 to halve the cycle load and free four input / output words on the S7-300 I area.
• Watchdog: keep watchdog enabled and set the master watchdog time (default 1.0 s) tight enough to drive the inverter into a fail-safe state on communication loss, but loose enough to ride through PLC pause / breakpoint conditions during commissioning.
• Fallback mode: if the slave firmware is unknown, install the GSD but verify the Ident_Number reads identically via "PLC → PROFIBUS Diagnostics" before connecting any motor.

Downloading and Verifying Communication

1. From HW Config, click Station → Save and Compile (Ctrl+S). The bottom panel must show 0 errors; warnings about HSA are tolerated but should be reduced.
2. Click PLC → Download to Target Unit. Select the correct PG/PC interface (e.g. PC Adapter (MPI) or CP 5611 (PROFIBUS)).
3. Bring the CPU to RUN; the SF / BF LEDs on the slave drive should extinguish within 2-3 scan cycles.
4. Open PLC → PROFIBUS Diagnostics in HW Config and confirm the new slave appears with state "active, no diagnosis" and a stable bus statistic (no repeat-failure frames).
5. Force a small setpoint in a watch-table by writing to the configured PQW word, verify the drive reacts, and back-read the drive actual value via PIW.

Diagnostic Tools and PROFIBUS Live Monitoring

For deeper analysis, use the SIMATIC NET "PROFIBUS Monitor" or any PI-conformant diagnostic tool. Standard toolset and interpretation points:

Troubleshooting Matrix

Field-Proven Pitfalls and Caveats

Several recurring issues appear repeatedly during field commissioning:

• Bitmaps missing. The GSD must be accompanied by a 1-bit-per-pixel BMP. STEP 7 silently ignores the device if it cannot load the icon, leading the engineer to suspect a corrupt catalog.
• Mixed GSD/GSG files. Older drives ship a .gsg (German) and .gse (English) variant. STEP 7 prefers the English file; both can be installed simultaneously for documentation completeness.
• GSD revision > project STEP 7. STEP 7 V5.5 will reject features declared as "DPV1 with safety" or "PROFIsafe" if the catalog does not know the identifier. Either apply the latest Service Pack for STEP 7 V5.5 or fall back to the standard PPO module list.
• Y-Link / DP/PA Coupler. When routing through a Y-Link to a downstream DP segment, the cyclic I/O length is limited to 244 bytes. PPO 5 (28 bytes) is well inside this limit, but stacking additional drive modules may exceed it.

FAQ