After the fix, an S7-1200 project can be moved with a compatible SIMATIC memory card sized for the complete project. The referenced controller manual lists 2 MB and 24 MB cards; 24 MB is the larger documented choice, but capacity alone does not establish CPU compatibility. Prepare the card for the required transfer function in the engineering software, reset or clear the destination as required by the transfer workflow, load the program, and verify the destination project before returning the machine to service.
Symptom interpretation
The term size limitation here can mean three different limits: the card's physical capacity, the CPU's support for a particular card order number, or the amount of load memory required by the compiled project. Treating these as one limit leads to incorrect purchasing decisions.
| Observation | Meaning | Required check |
|---|---|---|
| The project will not fit on a card | The compiled load requirement plus required card content exceeds usable capacity. | Read the compiled project size in TIA Portal and compare it with available card capacity. |
| The CPU does not accept the card | The card type, order number, preparation, or CPU compatibility is wrong. | Match the CPU catalog entry and hardware manual against the exact card order number. |
| The card fits, but the destination retains the old program | The card was not prepared for the intended transfer operation, or the required reset/load sequence was incomplete. | Check the card function selected in TIA Portal and repeat the documented destination-CPU sequence. |
| The copied program starts but the machine does not operate correctly | Program transfer succeeded, but hardware configuration or installation-specific data does not match. | Compare CPU type, configured modules, addresses, network settings, and retained values. |
Memory-card mechanism
A memory card does not perform an unrestricted clone of every property associated with a controller. It carries content prepared by the engineering system, while the CPU controls how that content is accepted, stored, and executed. The intended operation must therefore be selected before insertion into the destination CPU.
Program size is only one part of the decision. The destination must also accept the card and the generated hardware configuration. A project built for a different CPU or I/O arrangement can fit within the card capacity and still fail validation or produce configuration diagnostics.
Resetting the destination removes the conflict created by an existing application and allows a new program to be downloaded. Apply the reset only within the documented transfer procedure: it can remove the current user program and installation-specific retained data. Preserve the destination project and record values that must be restored before performing the operation.
Capacity and compatibility selection
Appendix A.12 of the referenced SIMATIC S7 S7-1200 Programmable Controller manual lists these SIMATIC memory cards:
| Order number | Listed capacity | Selection use |
|---|---|---|
6ES7 954-8LB00-0AA0 |
2 MB | Use only when the complete prepared content fits and the target CPU supports this order number. |
6ES7 954-8LF00-0AA0 |
24 MB | Provides more capacity for larger projects or additional card content, subject to CPU compatibility. |
For the two documented choices, 24 MB is the larger capacity. This is not a rule that every S7-1200 CPU accepts any card of that nominal size. Before ordering multiple cards, identify each CPU order number and consult its applicable hardware-manual revision or TIA Portal catalog entry. Match by Siemens order number, not merely by physical appearance or printed capacity.
Compile every intended project and read its load-memory requirement. Select a supported card with capacity above the complete prepared content, allowing room for any other intended files or service functions. Do not substitute an ordinary consumer card because it has the same form factor, and do not reformat a SIMATIC card with an operating-system format command.
CPU-to-CPU transfer procedure
A dedicated device described only as an “S7-1200 programmer” is not inherently required. What is required is TIA Portal and a supported way to prepare the SIMATIC memory card, such as a compatible computer card interface. Follow the manual for the installed CPU and TIA Portal release because card commands and displayed names can vary.
- Identify the source and destination CPU order numbers. Compare their firmware requirements, memory-card support, and configured hardware.
- Open the known-good source project in TIA Portal. Compile the hardware and software, then resolve compilation errors before creating the transfer media.
- Record installation-specific settings that may not be safely replaced: network addresses, device names, hardware substitutions, retained process values, recipes, and commissioning constants.
- Insert a supported SIMATIC memory card into the engineering workstation's compatible card interface. Use TIA Portal to prepare it for the intended project-transfer operation; copying project files through the operating-system file manager is not equivalent.
- Write the compiled project to the card and use the engineering software's completion or eject function before removing it.
- Place the destination equipment in a safe state. Stop the CPU and perform the reset or memory-clear operation required by the applicable transfer instructions.
- Insert the prepared card and execute the CPU's documented load sequence. Do not remove power or the card while the CPU indicates an active operation.
- After the CPU reports completion, follow the documented power, card-removal, and restart sequence. Do not assume the card must remain installed; that depends on how the card was prepared.
- Restore only the installation-specific values verified for the destination, then test the application before enabling automatic operation.
Numbered verification checks
- Check 1: card identity. Expect the printed order number to match a card supported by the exact destination CPU.
- Check 2: project capacity. Expect the compiled project and all prepared card content to fit within either the documented 2 MB or 24 MB capacity selected for the job.
- Check 3: compile result. Expect hardware and software compilation to finish without errors before writing the card.
- Check 4: transfer completion. Expect the CPU indication defined by its operating instructions to show that loading has completed, not that a card operation remains active.
- Check 5: online identity. Expect the online CPU type, hardware configuration, and loaded project identification to agree with the intended destination project.
- Check 6: diagnostics. Expect no unresolved configuration, memory-card, firmware-compatibility, or missing-module diagnostic entries.
- Check 7: controlled function test. Expect inputs, outputs, interlocks, networked devices, and commanded states to match the approved commissioning test before automatic operation.
Recurring transfer pitfalls
The most common purchasing error is treating megabytes as the only specification. Order-number support is the first gate; capacity is the second. Confirm both for every CPU variant before placing a combined order.
Another wrong practice is dragging project files onto the card in a desktop file manager. TIA Portal must create the controller-readable card structure and intended transfer function. Operating-system formatting can also make a valid industrial card unusable until it is correctly restored.
A transferred program is not automatically a valid machine clone. Different module populations, addressing, network identities, firmware requirements, or retained commissioning values can prevent startup or create unsafe commands. Keep an offline backup of both CPUs and compare the hardware configurations before clearing the destination.
Do not interrupt a card operation. Loss of power or premature card removal can leave the destination without a usable application. Read the CPU indicators according to its manual and act only after the documented completion state appears.
FAQ
Can I copy an S7-1200 program from one CPU to another with a memory card?
Yes, when TIA Portal prepares a supported SIMATIC memory card for project transfer and the destination CPU is compatible with the compiled hardware and software. Clear or reset the destination when required by the applicable loading procedure.
Does an S7-1200 need a special programmer to write the memory card?
A device identified only as an “S7-1200 programmer” is not inherently required. Use TIA Portal with a compatible card interface and prepare the card through the engineering software rather than copying files through the operating system.
Can I use the 24 MB card in place of the 2 MB card?
Use 6ES7 954-8LF00-0AA0 only when the exact CPU supports that order number; the referenced manual lists it as 24 MB, while 6ES7 954-8LB00-0AA0 is 2 MB. Final verification: go online and expect the destination CPU identity, hardware configuration, loaded project, and diagnostics to match the approved project.