Reading .pb5 Files from Siemens IM 308-3UC1 5V FLASH 256

Overview

The Siemens IM 308-3UC1 is a PROFIBUS DP master interface module for the SIMATIC S5 PLC family, including the S5-95U and the wider ET 200 distributed I/O architecture. The module stores its complete master configuration on a removable 5V FLASH 256 memory card, with the project archived as a single .pb5 file. Reading the .pb5 file out of the module is a routine engineering task required for backup, project replication, controller replacement, and migration of an existing PROFIBUS master configuration into a newer S7-based system.

Two proven methods exist for extracting a .pb5 file from an IM 308-3UC1 installation:

1. Upload the file from the IM 308-C's PROFIBUS port using COM PROFIBUS software and a PROFIBUS CP or Siemens PG.
2. Read the EPROM/FLASH directly with a Siemens PG or an external EPROM/FLASH reader after removing the card from the module.

Both methods require COM PROFIBUS, the Siemens configuration tool that defines DP masters, slaves, and bus timing, and that stores the project as a .pb5 file. COM PROFIBUS is not available as a free download and must be obtained through your nearest Siemens representative. The official Siemens Industry Online Support portal provides current ordering and licensing details for COM PROFIBUS and for the ET 200 Distributed I/O System with IM 308-C and S5-95U manual.

Prerequisites

Before attempting either read-out method, confirm the following hardware and software items are available:

For Method 2 (direct EPROM read), you also need either a Siemens PG with EPROM/FLASH programmer support, or a third-party EPROM/FLASH programmer capable of reading 5 V parallel FLASH devices. Verify the device ID of the FLASH on the card before selecting a programmer algorithm; mismatched algorithms will return all-0xFF or garbled data even when the card is healthy.

Understanding the 5V FLASH 256 Memory Card

The 5V FLASH 256 card is a 256 Kbit battery-free FLASH memory module that plugs into the IM 308-3UC1's front card slot. The card stores the COM PROFIBUS project as a single .pb5 file, which the IM 308-C reads on power-up to load its master configuration, slave list, bus parameters, and diagnostic addresses.

Key electrical and operational characteristics of the 5V FLASH 256 card:

• Logic level: 5 V only. The card slot of the IM 308-C is hard-wired for 5 V operation.
• Capacity: 256 Kbit (32 Kbyte). Sufficient for typical DP master configurations with up to 122 slave slots.
• Non-volatile: Data is retained without a battery. Programming and erase are controlled by the IM 308-C firmware.
• Removable: The card can be pulled from the module for offline read-out or duplication.

Removing the card does not erase its contents. The IM 308-C retains the project in non-volatile FLASH until it is explicitly reprogrammed through COM PROFIBUS. A cold start of the S5 PLC with the card removed will leave the IM 308-C without a master configuration; the module will not join the DP segment and will report a configuration fault on its status LEDs.

The .pb5 File Format

The .pb5 extension is the standard COM PROFIBUS project file. The file is a binary database that contains:

• DP master parameters (PROFIBUS address, baud rate, slot time, quiet time, TSDR, GAP factor, retry count)
• Slave list (PROFIBUS addresses, GSD references, I/O slot mapping, diagnostic slots)
• Bus timing and diagnostic configuration
• User comments and project metadata

The same .pb5 file is consumed by the IM 308-C at boot and by COM PROFIBUS for offline editing. A backup .pb5 file can be loaded onto a fresh 5V FLASH 256 card to clone a working master configuration, or imported into COM PROFIBUS for offline analysis and modification. The .pb5 file is the canonical exchange format for S5-era DP master projects and is the only file type that the IM 308-C card slot will accept for programming.

Cable Selection and PROFIBUS Interface Options

Either a standard PROFIBUS cable with two D-sub 9-pin connectors, or an MPI/DP cable such as the 6ES7 972-0CB20-0XA0, can be used to connect the host PC to the IM 308-C PROFIBUS port. The following table compares the two cable approaches:

For a point-to-point backup, an MPI/DP cable 6ES7 972-0CB20-0XA0 between the PC's CP and the IM 308-C's PROFIBUS port is typically the simplest arrangement, particularly when the IM 308-C is not connected to a live DP segment. A standard MPI cable generally also works for the upload, as the IM 308-C supports MPI-mode addressing for the configuration read.

Method 1: Upload .pb5 via the IM 308-C PROFIBUS Port

This method is the preferred approach when the IM 308-C is installed in a working system, because it does not require removing the memory card and it can be performed while the S5 PLC is in RUN (with the project live on the bus).

Step 1 - Install COM PROFIBUS on the engineering PC

1. Obtain a licensed copy of COM PROFIBUS from your Siemens representative or through the Siemens Industry Online Support portal.
2. Install the package, including the CP 5611/CP 5613/CP 5512 device driver.
3. Confirm the CP is recognised in the Windows Device Manager and in the COM PROFIBUS "Set PG/PC Interface" dialog.
4. Verify the CP firmware is at a level supported by your COM PROFIBUS release; older CP firmware may not enumerate correctly under newer COM PROFIBUS versions.

Step 2 - Connect the PC to the IM 308-C

1. Connect the PROFIBUS cable from the PC's CP to the IM 308-C's PROFIBUS port.
2. If connecting to a live DP network, observe the segment topology and bus terminator rules.
3. If connecting point-to-point, enable bus terminators at both ends and verify the IM 308-C's PROFIBUS address (default is typically 1, but verify on the module's DIP switch).

Step 3 - Open COM PROFIBUS and select the upload path

1. Launch COM PROFIBUS.
2. From the menu, choose File > Upload from DP master / IM 308-C (exact wording varies by COM PROFIBUS version).
3. Select the PC PROFIBUS CP and the IM 308-C's PROFIBUS address (default 1, but verify on the module's DIP switch).
4. Set the upload baud rate to match the IM 308-C; the COM PROFIBUS upload routine will normally auto-detect, but on marginal links you may need to lock the baud rate manually.

Step 4 - Read the .pb5 file from the FLASH card

1. COM PROFIBUS reads the configuration from the IM 308-C's 5V FLASH 256 card over the PROFIBUS link.
2. Save the resulting project as a new .pb5 file on the engineering PC (for example, IM308C_backup_YYYYMMDD.pb5).
3. Note the file size, baud rate, master address, and COM PROFIBUS version in a project log for traceability.
4. Store the .pb5 file in a versioned project archive - never overwrite the only known-good copy.

Method 2: Read the FLASH/EPROM Card Directly

This method is used when the IM 308-C is not reachable over PROFIBUS, when the upload fails, or when an exact byte-level image of the card is required for forensic or cloning purposes.

Step 1 - Power down the S5 rack

1. Bring the S5 PLC to a safe state per site procedure (typically STOP with all controlled outputs in a known-safe state).
2. Remove power from the rack.
3. Wait for the IM 308-C's status LEDs to extinguish before removing the card.
4. Document the card slot position and orientation - the 5V FLASH 256 card is keyed, but the keyed notch must be aligned for re-insertion.

Step 2 - Remove the 5V FLASH 256 card

1. Open the card slot cover on the IM 308-3UC1 front panel.
2. Pull the 5V FLASH 256 card straight out of the slot using the ejector tab; do not rock the card, as the edge connector pins can bend.
3. Place the card in an anti-static holder.

Step 3 - Read the card with a Siemens PG or external programmer

1. Insert the card into a Siemens PG that supports the IM 308-C card type, OR insert it into an external EPROM/FLASH programmer socket.
2. Use the PG's EPROM/FLASH driver or the external programmer software to read the full device into a binary image.
3. Save the binary image. Note that this raw image is not a .pb5 file; it is a flat binary dump of the FLASH contents including header, .pb5 payload, and any trailing pad bytes.
4. Record the FLASH device ID and the programmer algorithm used in the project log.

Step 4 - Convert the binary dump to .pb5 (if required)

1. Open COM PROFIBUS.
2. From the menu, choose File > Import from EPROM/FLASH image (or equivalent "import binary" command; exact wording varies by version).
3. Point COM PROFIBUS at the saved binary dump.
4. Save the imported configuration as a new .pb5 file.

Verification

After either method, verify the extracted configuration is usable:

1. Open the saved .pb5 file in COM PROFIBUS.
2. Confirm the master PROFIBUS address, baud rate, and slave list match the live system.
3. Check the file size against a known-good backup; a corrupted or truncated upload will typically be smaller than expected.
4. Verify that the GSD file references in the .pb5 match the GSD versions installed under COM PROFIBUS - a missing GSD will cause slave entries to be displayed as "unknown device".
5. Optionally, load the .pb5 file onto a spare 5V FLASH 256 card and install it in a bench IM 308-C; the module should boot with the same master address and pass its self-test.
6. Compare the offline master parameters in COM PROFIBUS against the live bus diagnostics (PROFIBUS tracer or BT 200) if the IM 308-C is still on a live network.
7. Confirm the .pb5 file opens cleanly in COM PROFIBUS with no parse warnings in the message log.

Troubleshooting Matrix

Best-Practice Notes

• Always perform a read-out immediately after any change to the IM 308-C configuration, and store the .pb5 file under a date-stamped name. Do not overwrite the previous good copy until the new file has been opened and verified in COM PROFIBUS.
• Keep a binary dump (Method 2) of the 5V FLASH 256 card in addition to the .pb5 export. The .pb5 file is a COM PROFIBUS representation; the binary dump is the only authoritative image of the card.
• When cloning a master to a new card, program the new card with COM PROFIBUS rather than copying the binary dump directly. A direct binary copy can carry over card-specific serialisation or write-protect state that prevents the new card from booting.
• If the IM 308-C is on a live DP network, do not change the master PROFIBUS address or baud rate from the IM 308-C side while the upload is in progress. Doing so will drop the upload and may disrupt the running slaves.
• Document the COM PROFIBUS version, CP type, CP firmware, and the IM 308-C firmware/hardware release (for example, 6ES5 308-3UC1) alongside every backup. This is essential when restoring a project years later against newer COM PROFIBUS releases.

Related Configuration Workflow

Once the .pb5 file is read out, it can be opened in COM PROFIBUS for the typical follow-on engineering tasks:

• Slave replacement: substitute a newer slave by mapping its GSD into the existing slot, then re-program the 5V FLASH 256 card and reload the IM 308-C.
• Migration to S7: import the .pb5 into a STEP 7 / TIA Portal PROFIBUS view, where the GSD-based slave list is preserved and the master can be re-homed on a CP 443-5 Extended or a CPU with integrated DP master port.
• Documentation: export the master and slave parameters from COM PROFIBUS to a PDF or RTF report and attach it to the project archive alongside the .pb5 file.

For the ET 200 distributed I/O topology, the IM 308-3UC1 acts as the DP master and the ET 200 stations (with IM 151 / IM 153 interface modules) are its DP slaves. The .pb5 file therefore carries the entire DP network definition, not just the master's own parameters. Treat the .pb5 file as the single source of truth for the DP segment when handing the system over to a new maintainer.

Frequently Asked Questions