How to Read S7-300 CPU Firmware in TIA Portal and Add Legacy CPUs

How to Read S7-300 CPU Firmware in TIA Portal and Add Legacy CPUs via HSP

This field reference covers the two questions every S7-300 engineer eventually faces when migrating a Classic STEP 7 project into the Totally Integrated Automation Portal (TIA Portal):

1. How to read the firmware (FW) version of an S7-300 CPU directly from TIA Portal.
2. How to add an S7-300 CPU that is missing from the TIA Portal hardware catalog, in particular legacy 315-2PN/DP class devices that pre-date the TIA release window.

Both tasks appear trivial, but the moment a CPU type is missing from the catalog or returns an "unsupported device" error, hours of engineering time evaporate. The procedures below are the only Siemens-supported routes and use only official deliverables: Online & Diagnostics, the Hardware Support Package (HSP) mechanism, and the TIA Portal Compatibility Tool.

1. Prerequisites

Before reading firmware or installing an HSP, confirm the following baseline items are in place. Skipping any one of these typically produces confusing, downstream errors.

2. Reading CPU Firmware via Online & Diagnostics

The fastest way to read the firmware version of an online S7-300 CPU is through TIA Portal's Online & Diagnostics view. This works without an open project, without a configured station, and without configuration control. It is the equivalent of the old STEP 7 "PLC > Diagnostic/Hardware" dialog.

2.1 Step-by-step procedure

1. Open TIA Portal. The project state does not matter — you can use a freshly created empty project.
2. From the project tree, expand Online & Diagnostics on the left (or right-click an empty project and select Go online after first creating a new device).
3. In the Online menu, choose Online access. Expand the active network interface (PROFINET, MPI, or PC-Adapter).
4. Click Update accessible devices (the eye/refresh icon). TIA will broadcast DCP/RPC discovery and list every reachable S7-300 CPU with its IP, rack, slot, and device name.
5. Select the target CPU in the accessible devices table.
6. Click Connect online (the "plug" icon in the toolbar).
7. Once online, TIA opens the Online & Diagnostics editor for the selected CPU. The first node displayed is Diagnostics.
8. Navigate to Diagnostics > General (or the equivalent Device Information tab on newer TIA versions).
9. Read the firmware version from the Module information block. Typical fields include:
   • Module name — e.g. CPU 315-2 PN/DP
   • Order number (MLFB) — e.g. 6ES7 315-2EH14-0AB0
   • Firmware — e.g. V3.3.13 (or V2.6.9, V4.2.0 depending on model)
   • Hardware — e.g. 4 (sub-version of the module)
   • Serial number
   • Boot loader version

2.2 Alternative: read firmware from a project device

If the S7-300 CPU is already inserted in the current project, the firmware can also be read offline-but-online-verified:

1. Open the device configuration (double-click Device & Networks).
2. Click the CPU icon on the rack.
3. Open the Properties inspector at the bottom of the screen.
4. Select General > Identification > Module identification.
5. Click Go online to refresh the values from the physical device.
6. The Firmware version field updates with the live value, e.g. V3.3.17.

3. Interpreting the S7-300 Firmware String

Siemens firmware strings for S7-300 CPUs follow a fixed convention that maps directly to the order number (MLFB). Decoding the string determines which TIA Portal version is required and whether an HSP is needed.

The first digit of the firmware version (V2.x, V3.x, V4.x) is significant:

• V2.x — older generation; frequently unsupported in TIA V15+.
• V3.x — fully supported in TIA V13 SP1 through V16 with the matching HSP.
• V4.x — common on the 31xT technology CPUs; TIA V15.1+ required.

4. Adding Legacy S7-300 CPUs to the TIA Portal Hardware Catalog

When the target CPU is not in the device catalog, TIA rejects it with the message "The device is not in the hardware catalog" or "HSP is required". There are exactly two supported fixes.

4.1 Option A — Install a Siemens Hardware Support Package (HSP)

Siemens releases Hardware Support Packages on a regular cadence (HSPxxxx numbers). Each HSP adds a batch of new module types, firmware versions, and (rarely) bug fixes to the device catalog. HSPs are additive — older modules remain available after newer HSPs are installed.

HSPs are version-locked to a TIA Portal major version. An HSP for TIA V16 will not install on V14. The supported TIA branches historically are: V11, V12, V13, V13 SP1, V14, V14 SP1, V15, V15.1, V16, V17, V18.

4.2 Option B — Remain on Classic STEP 7

If the S7-300 CPU has a firmware version below the TIA minimum, it is not projectable in TIA Portal at all. Examples include early CPU 314 with FW < V2.0 and pre-V3 firmware on the 31x-2DP family. In that case the only option is STEP 7 V5.5 (Classic). The compatibility tool will list this explicitly as "No TIA Portal support".

5. Installing a Hardware Support Package (HSP) — Step-by-Step

1. Close all running instances of TIA Portal on the engineering station.
2. Open the Siemens Industry Online Support portal and navigate to Support > Downloads > Automation Technology > TIA Portal.
3. Filter by category "Hardware Support Package" for your TIA Portal version (e.g. TIA Portal V16 / Hardware Support Package).
4. Download the most recent cumulative HSP. The file name follows the convention HSP_V16_xxxx.exe for V16, or SIMATIC_HSP_Vxx_xxxx.exe for older branches.
5. Right-click the EXE and choose Run as administrator. The HSP installer is its own self-extracting application; it is not installed from inside TIA.
6. Follow the wizard. The installer writes the HSP to:
   • %ProgramFiles%\Siemens\Automation\Portal Vxx\Hsp (TIA V16+)
   • %ProgramFiles(x86)%\Siemens\Automation\Portal Vxx\Hsp (TIA V13/V14)
7. Restart the engineering station if prompted.
8. Open TIA Portal.
9. From the menu, choose Options > Support Packages. The Support Packages dialog lists every installed HSP with its Status column.
10. Tick the HSPs to activate, then click Apply. TIA copies the catalog additions into the active project database.
11. Confirm the result by opening Devices & Networks > Add new device and searching for the previously-missing CPU. The exact MLFB should now appear under the manufacturer filter SIMATIC S7-300.

6. Using the TIA Portal Compatibility Tool

The SIMATIC S7-300/S7-400 / TIA Portal Compatibility Tool is the only authoritative source for the question "Can TIA Portal Vx.y program CPU MLFB z with FW a.b?". The tool is a parameterized web form on the Siemens Industry Online Support site.

6.1 Recommended workflow

1. Open the compatibility tool URL above.
2. On the left column, select CPU family (S7-300, S7-400, ET200S, WinAC, …).
3. Select the CPU type (e.g. CPU 315-2 PN/DP).
4. Select the firmware version from the dropdown — match what you read in step 2 above.
5. The right column lists every STEP 7 / TIA Portal version with a colored bullet:
   • ● Green — fully supported.
   • ● Orange — supported with limitations (read tooltip).
   • ● Red — not supported.
6. Hover over any bullet to see the precise limitations: missing system functions, restrictions on OB usage, blocked instructions, etc.

The tool is updated whenever a new TIA Portal service pack ships, but there is a delay of several weeks after a major TIA release. If a CPU is shown as not supported but you have a recent HSP installed, refresh the page and check the Release notes link of the HSP for the exact module list.

7. Adding Third-Party Devices (GSD Import)

If the missing device is not a Siemens S7-300 but a third-party PROFINET or PROFIBUS slave, the catalog update route is different. TIA Portal uses GSD/GSDML files instead of HSPs.

1. Obtain the GSDML file (PROFINET) or GSD file (PROFIBUS) from the device vendor. File extensions: .xml for PROFINET, .gsd or .gsd.gz for PROFIBUS.
2. In TIA Portal, open Options > Manage general station description file (GSD).
3. Browse to the GSD file and click Install.
4. Restart TIA Portal if prompted.
5. The new device appears in the hardware catalog under Other field devices > PROFINET IO > [Vendor] or PROFIBUS DP > [Vendor].

8. Common S7-300 Firmware Field Examples

9. Verification After Firmware Read or HSP Install

Run the following checks in sequence to confirm a clean read or install.

1. Online & Diagnostics > Module information displays a non-empty Firmware field. Record the value.
2. Compatibility Tool confirms the CPU + FW pair is green for the installed TIA version.
3. Add the CPU to the project via Add new device > SIMATIC S7-300 > CPU 31x > [Order number]. TIA should accept the MLFB and create a station.
4. Go online with the new project. The online compare should show Online/offline identical for the CPU object.
5. Run a single Download to device (test build) — this is the real proof that the firmware and TIA version are aligned.
6. Check Online & Diagnostics > Diagnostic buffer for the entry "Download completed" with status OK.

10. Troubleshooting Matrix

11. Edge Cases and Field-Proven Caveats

11.1 S7-300F / F-CPU handling

Safety CPUs (CPU 315F-2 PN/DP, CPU 317F-2 PN/DP, CPU 319F-3 PN/DP) require the Failsafe option package on top of TIA Portal. The HSP is not enough; without Failsafe, the F-CPU appears in the catalog but cannot be programmed. Confirm Options > Installed software lists S7-PLCSIM and the F-Configuration Pack before commissioning.

11.2 Technology CPUs (T-CPUs)

The CPU 315T-2 DP and CPU 317T-2 DP technology CPUs need the S7-Technology option. Without it, the catalog entry exists but motion blocks are greyed out in the program editor.

11.3 R/H (Redundant) systems

CPU 414-4H, CPU 417-4H redundant CPUs are out of scope for S7-300 but appear in the same TIA Portal. The S7-400H option package is mandatory; standard TIA Portal cannot download a redundancy project.

11.4 Firmware updates

To upgrade an S7-300 CPU firmware, use SIMATIC Automation Tool, TIA Portal's Online & Diagnostics > Firmware update tab, or a SIMATIC Memory Card with a service pack. Never downgrade — Siemens does not support downgrade paths and the diagnostic buffer will flag the attempt as a module fault.

11.5 The "CPU unknown" message

If a CPU returns CPU unknown in Accessible devices, the cause is one of three:

1. Stale ARP cache on the engineering station — run arp -d * in an elevated command prompt, then refresh.
2. CPU is in a different VLAN — enable DCP relay or move the PG/PC.
3. CPU firmware is older than the lowest FW that TIA can identify — use STEP 7 Classic or the SIMATIC Automation Tool to read the FW via the device's own web server.

12. Field Commissioning Checklist

1. Read the FW of the S7-300 CPU via Online & Diagnostics and write it on the as-built sheet.
2. Cross-check the FW against the TIA Portal Compatibility Tool for the TIA version in use.
3. If the CPU is missing from the catalog, install the matching HSP from the Siemens support portal.
4. Verify the catalog now lists the exact MLFB.
5. Open a new project, add the CPU, compile, and download.
6. Confirm Online/offline identical and clear diagnostic buffer entries.
7. Document the TIA version, HSP number, and CPU FW in the project cover sheet for future migration work.

With these procedures the S7-300 firmware is always known, the catalog is always complete, and any "unsupported device" message has a documented, Siemens-supported fix path.