Resolving siem805b.gsd Missing Error on Siemens IM308C Profibus

1. Problem Overview: Missing Legacy GSD on S5 / IM308C Upload

A "GSD file missing" error during Profibus upload on a Siemens IM308C master typically surfaces when the COM Profibus archive references a slave whose device description file is not present in the configured GSD path. In this case the missing filename is siem805b.gsd, the legacy Siemens device-description file for the MicroMaster 4 (MM4) Profibus DP slave module. S5 PLC archives created before Siemens reorganized its naming scheme still hold the old string; COM Profibus cannot reconcile it against the current si0280b5.gsd automatically, so upload halts at the IM308C configuration block. The problem compounds when a phased-out SIMOREG 6RA70 DC Master is replaced with a SINAMICS DCM 6RA80 in the same cabinet: the new drive requires its own GSD plus the engineering-extension file si03816a.gse, and without resolving the legacy GSD reference first, COM Profibus refuses to load the master project and the SINAMICS DCM station record cannot be added or modified.

2. Profibus GSD File Structure and Siemens Naming Convention

A Profibus GSD file is a plain-text, ASCII-formatted device description. Its structure is defined in IEC 61784-1 and the PNO profile guideline order number 3.092 issued by the Profibus Nutzerorganisation (PNO). Siemens implements the file with the standard keyword set including Vendor_Name, Model_Name, Revision, Ident_Number, Baudrates, Max_Diag_Data_Len, SlotDef, ModuleDef, and EndModule. COM Profibus parses each file to construct the slave catalog visible in the configuration tree. The vendor master database maintained by PNO allocates a unique Ident_Number for every Profibus device class; Siemens AG holds an allocation range beginning with 0x0800, and the MM4 Profibus CB module is registered under Ident_Number 0x0805.

Siemens has used two naming schemes in parallel since the late 1990s:

• siem<ID><rev>.gsd - older convention; the trailing letter encodes a hardware or firmware revision. Example: siem805b.gsd.
• si<group><variant><rev>.gsd - newer convention; the 4-digit group number derives from the PNO Ident_Number range assigned to Siemens. Example: si0280b5.gsd.

File naming is purely cosmetic; the device functionality described inside is identical for the same Ident_Number. Replacing the legacy file in the project archive without changing the internal Ident_Number is the recommended remediation.

3. Locating the siem805b.gsd or si0280b5.gsd File

The authoritative sources for Siemens Profibus GSD files are:

1. Siemens Industry Online Support (SIOS) - entry ID 11173887 maintains a master list of GSD files and associated DP slave libraries. Search for "MicroMaster 4 GSD" or "si0280b5". The package typically bundles the GSD plus a bitmap (BMP) and a Type file. Reference: Siemens Industry Online Support.
2. STARTER / Drive ES shipping DVD - SINAMICS DCM ships with the SSP (SINAMICS Support Package) on the STARTER installation medium. The SSP contains both GSD and GSE for every DCM firmware release. Mount the ISO and browse to SSP_DCM\GSD.
3. SIMATIC Manager / COM Profibus installation media - older S5 installations included a GSD folder on the installation CD. Copy siem805b.gsd from \S5\COMPROFIBUS\GSD if it exists in your archive.
4. Vendor Service Pack on legacy S5 floppy - S5-PG installations in the late 1990s shipped with an "S5 DP Slave Library" floppy. The file is still usable provided the checksum matches the 1.x revision family.
5. Siemens Product CM (Configuration Manual) DVDs - some drives ship a separate configuration manual DVD containing the GSD inside the PROFIBUS\GSD directory.

After downloading, copy the file into the directory configured in COM Profibus under Options > GSD Path. The default location on a Windows XP installation is C:\S5W\COMPROFIBUS\GSD. Restart COM Profibus so it rescans the catalog before the next upload attempt.

When the legacy siem805b.gsd cannot be obtained but the new si0280b5.gsd is available, perform an explicit alias rewrite within the project database. Open the COM Profibus project, right-click the MicroMaster 4 station entry, and select Properties > Slave Type. The dialog shows the internal Ident_Number; if it matches 0x0805 (Siemens PNO assignment for MM4), replace the legacy file pointer with si0280b5.gsd and re-save the project. This binds the new file to the same Ident_Number without requiring a project rewrite.

; Excerpt of typical Siemens GSD structure
#Profibus_DP
Vendor_Name = "Siemens AG"
Model_Name = "MICROMASTER 4"
Revision = "1.0"
Ident_Number = 0x0805
Protocol_Ident = 0
Station_Type = 0
Baudrates = 9.6 19.2 45.45 93.75 187.5 500 1500 3000 6000 12000
Max_Diag_Data_Len = 32
Module = "PPO 1: PKW + 2 PZD" 0xF3,0xF1
EndModule

4. IM308C Master Configuration Considerations

The IM308C is the SIMATIC S5 DP master module. It is installed in the S5-115U, S5-135U, or S5-155U central rack and acts as the gateway between the S5 CPU and the Profibus-DP segment. From the COM Profibus perspective, the IM308C is the master station; the MM4 and SINAMICS DCM are slave stations configured on its DP segment. The module occupies a slot in the S5 rack and is addressed by the CPU as a digital I/O block; standard addressing in the S5 environment places it at P/Q area slots 0-255.

Configuration parameters to verify before any upload:

• Station Address - default 1, range 1-126 for DP-V0/V1 master.
• Baud Rate - supported 9.6 kbps to 12 Mbps. The MM4 module supports all standard rates; the SINAMICS DCM CBC Profibus option supports the same range.
• Bus Parameters - slot time, min station delay, quiet time, and target rotation time must be compatible with the slowest slave. COM Profibus auto-calculates these from the master/slave list using the configured baud rate and the number of stations.
• Diagnostic LED interpretation - BF (Bus Fault) steady indicates physical layer or configuration fault; this is the LED most likely to illuminate after a failed upload.
• Slot time (Tsl) - calculated from cable length and number of repeaters. Default values are auto-computed but can be overridden under Bus Parameters > Slot Time.

The IM308C database limits the number of slaves per segment to 124 (addresses 0-126 minus master). The IM308C supports DP-V1 read/write services required by SINAMICS DCM for parameter access from STARTER. Make sure the firmware on the IM308C is at least the 3.x revision if DP-V1 acyclic services will be used; older firmware falls back to DP-V0 cyclic-only and STARTER will report a parameter channel failure.

5. SINAMICS DCM Migration from SIMOREG 6RA70

Replacing a SIMOREG DC-Master (6RA70 series) with a SINAMICS DCM (6RA80 series) on an existing Profibus segment requires more than swapping the drive. The GSD file, the Ident_Number, the parameter number (PNU) mapping, and the process data word layout all change. The result is that the new drive cannot simply inherit the old slave station record.

Migration procedure when a 6RA70 is replaced in place by a 6RA80 on the same Profibus segment:

1. Export the current DP slave record from the COM Profibus project to a backup file.
2. Delete the 6RA70 slave entry from the IM308C master configuration.
3. Install the SINAMICS DCM SSP for STARTER. The SSP places the new GSD into ...\Starter\GSD and the matching GSE into ...\Starter\Engineering\GSE.
4. Re-scan the COM Profibus catalog so the new DCM GSD appears in the slave list.
5. Add a new slave at the next free DP address (avoid reusing the 6RA70 address until the new drive is fully commissioned to prevent address collisions during the cutover).
6. Import the new GSD, configure the process data slots (Standard Telegram 1 or Telegram 5 for most field-oriented applications), and download the master project to the IM308C.
7. Commission the DCM with STARTER using the GSE file for parameter access.

6. MicroMaster 4 Profibus DP Slave Module Wiring

The MM4 inverter communicates on Profibus via the CB-Profibus option board. The board sits in the option slot of the MM4 chassis and presents a 9-pin D-sub connector on the bottom of the drive. Wiring points to verify during commissioning:

• Bus termination - the first and last physical station on the segment must have termination ON. The MM4 CB has a switch on the option board; the default position varies, so verify per station.
• Shield grounding - the Profibus cable shield must be clamped to the sub-D connector housing at every station using a metallized hood. Shield continuity to cabinet ground via the connector housing is required.
• Station address - set via the MM4 parameter P0918 (CB-Profibus address). Address range 1-126. Address must be unique on the segment.
• Baud rate - MM4 auto-detects between 9.6 kbps and 12 Mbps. No parameter needed.
• Repeater placement - between two repeaters, or between master and the first repeater, the maximum trunk is 100 m at 12 Mbps; the maximum number of repeaters in series is 9 (10 segments total).

For a typical 12 Mbps DP segment using standard Profibus cable (violet cable type A per IEC 61158), the maximum trunk length is 100 m without repeaters. The MM4 supports up to 32 stations per segment; a maximum of 126 stations can be addressed when repeaters or fiber-optic couplers are used. Cable type A is the recommended medium: 22 AWG conductor, characteristic impedance 135-165 ohms, loop resistance 110 ohm/km maximum, capacitance 30 pF/m maximum.

7. COM Profibus Upload Workflow

The proper sequence to resolve the missing GSD and complete the upload is:

1. Open COM Profibus on the S5 PG.
2. Select File > Open Project and load the master project (.s5d or .pbf file).
3. If a missing-GSD error appears, click OK and proceed to Options > GSD Path.
4. Add the directory containing si0280b5.gsd (and any DCM GSD / si03816a.gse). Multiple directories can be added; COM Profibus searches them in the listed order.
5. Click File > Read Slave Configuration from Master (Upload).
6. If the upload still fails on the MM4 station, open the station's Properties dialog, navigate to Slave Type, and select the new GSD from the catalog. Save the project.
7. Retry the upload. With the correct GSD in the path, COM Profibus parses the slave I/O map and completes the upload within 30-90 seconds depending on segment baud and number of slaves.

When COM Profibus reports the upload as successful, validate by exporting the configuration to a printable text file. Compare station addresses and slot configurations against the physical bus to ensure no address drift. The upload report is stored in the same project directory under .log and lists every diagnostic message from each slave.

8. Process Data Slot Configuration

Both the MM4 and the SINAMICS DCM use modular Profibus slot definitions. The default slot table for an MM4 with PKW+PZD channel is 8 PZD out / 8 PZD in plus a parameter channel (PKW). The SINAMICS DCM by default uses Telegram 5 (6 PZD out / 6 PZD in) but can be switched to Telegrams 1, 2, 20, 102, 103, 105, 106 via the DCM parameter p0922.

The IM308C master must be configured with a slot table that matches the telegram selected on the drive. A mismatch triggers a "Configuration Fault" diagnostic from the IM308C and the BF LED illuminates. When migrating from a 6RA70 with 4 PZD to a 6RA80 with 6 PZD, the master project must add the additional words on both directions or the drive will reject the cyclic data.

9. Diagnostic LED Matrix for IM308C and Slaves

10. STARTER Commissioning Sequence for SINAMICS DCM

1. Launch STARTER and open or create the DCM offline project.
2. Configure the device version, firmware release, and matching SSP files. The SSP file naming convention is SSP_DCM_V<version>.zip.
3. Set the Profibus station address via parameter p0918 to match the master configuration.
4. Set the PROFIBUS interface selection via p2030 = 2 (PROFIBUS).
5. Select the process data telegram via p0922 (Telegram 5 default).
6. Configure the control and status word mapping (r0050 for status, control word received from master on PZD1).
7. Configure the encoder interface, armature current, and field current parameters per the armature/field nameplate.
8. Save the project and go online via the Profibus connection to the IM308C master.
9. Read the parameter r2050[0..5] and verify cyclic process data is updating.
10. Perform a controlled motor test at low speed, verify direction, ramp behavior, and ramp-down.

; SINAMICS DCM key parameters
p0918 = 5            ; Profibus station address
p2030 = 2            ; Interface selection = Profibus
p0922 = 5            ; Telegram 5 (6 PZD out / 6 PZD in)
p2051[0] = r2050[0]  ; Status word mapping
p0840 = 2090.0       ; ON/OFF1 command source
p1001 = 0            ; Speed setpoint default
r2050[0..5]          ; Process data status words (read)

11. MicroMaster 4 Profibus Parameter Reference

12. Error Matrix and Diagnostics

13. Verification and Commissioning Checklist

After resolving the GSD issue and completing the upload, validate the configuration with this checklist:

1. Confirm the IM308C BF LED is off and the SF (System Fault) LED is off during normal operation.
2. Run File > Compare Project with Connected Master in COM Profibus. The result should be "no differences".
3. Verify each slave station appears in the live diagnostic list with the expected station address and module type.
4. For the SINAMICS DCM, go online with STARTER. Read the parameter r2050[0..5] and confirm the process data values update as the drive runs.
5. For the MM4, read parameter r2051 and r2053 to verify the cyclic PZD is reaching the inverter.
6. Force a controlled stop from the S5 program and verify the drive enters its stop state within the configured ramp time.
7. Document the final GSD file versions, firmware revisions, and slot configurations in the plant asset register.
8. Run a 24-hour burn-in with the drive at 50% rated load to verify cyclic communication stability and PZD consistency.

14. Frequently Asked Questions