An ET 200S station identified as IM 151-7 CPU, type 6ES7 151-7AA20-0AB0, should use a compatible Micro Memory Card (MMC) when the application must survive loss of the power supply. The available evidence reports a maximum supported MMC capacity of 8 Mbyte.
Identify the CPU Before Selecting a Retention Method
Do not treat this unit as an unspecified legacy S7-300 CPU. The reported device is an ET 200S IM 151-7 CPU, so select memory and loading procedures for type 6ES7 151-7AA20-0AB0. Advice about installing a 3.6 V battery was raised only as a hypothesis for older CPUs and is not established for this identified module.
| Item | Evidence-based requirement |
|---|---|
| CPU | ET 200S IM 151-7 CPU |
| Type number | 6ES7 151-7AA20-0AB0 |
| Retention medium | Compatible MMC |
| Reported maximum capacity | 8 Mbyte |
| Exact compatible card part number | Not provided; verify before procurement |
Load the Project to the MMC
Downloading only to working memory does not establish that the project will remain available after power removal. Store the project on the MMC using the engineering software's documented MMC loading function.
- Confirm that the nameplate shows type 6ES7 151-7AA20-0AB0.
- Select an MMC explicitly compatible with this ET 200 CPU and do not exceed the reported 8 Mbyte limit. The evidence does not provide an order number, so verify compatibility in the applicable Siemens documentation before ordering.
- Use the engineering software's MMC load procedure to write the project to the card. The evidence does not specify the software version or exact menu command.
- Confirm that the load completes without an error before removing power.
Verify Retention After a Power Cycle
Remove and restore the CPU power under controlled conditions, then confirm that the CPU starts with the intended application without another download. Check operating mode and application behavior rather than relying only on the presence of the card. If the program is not restored, recheck card compatibility, confirm that the project was written to the MMC rather than only downloaded to working memory, and record any diagnostic indication before changing hardware.
FAQ
Which memory card does an ET 200S IM 151-7 CPU use for program retention?
The evidence identifies a compatible MMC as the retention medium. Verify the exact Siemens order number for type 6ES7 151-7AA20-0AB0 before procurement.
What is the maximum MMC capacity for 6ES7 151-7AA20-0AB0?
The reported maximum capacity is 8 Mbyte. Do not select a larger card without confirmation in the applicable Siemens documentation.
Does the IM 151-7 CPU require a 3.6 V battery to retain its program?
The battery suggestion concerned an unconfirmed hypothesis about older CPUs. For the identified IM 151-7 type, the evidence-supported action is to load the project onto a compatible MMC and verify retention with a controlled power cycle.