Provides twenty onboard digital points in a compact standard CPU.
Technical Summary
6ES7288-1ST20-0AA1 is the Siemens SIMATIC S7-200 SMART CPU ST20. The DC/DC/DC article uses a 20.4 to 28.8 V DC supply with 12 onboard 24 V DC inputs and 8 onboard 24 V DC transistor outputs.
The ST20 provides 20 KB of program and data memory and is engineered with STEP 7-Micro/WIN SMART. Ethernet and RS485 communication are integrated into the S7-200 SMART CPU platform.
The 0AA1 generation supports firmware V2.7 and cannot be downgraded to V2.6 or earlier.
Specifications
| Manufacturer | Siemens |
|---|---|
| Exact article number | 6ES7288-1ST20-0AA1 |
| Product family | SIMATIC S7-200 SMART |
| CPU designation | CPU ST20 |
| CPU architecture | DC/DC/DC |
| Supply voltage | 20.4 to 28.8 V DC |
| Digital inputs | 12 onboard, 24 V DC |
| Digital outputs | 8 onboard transistor outputs, 24 V DC |
| Program and data memory | 20 KB |
| Industrial Ethernet interfaces | 1 |
| RS485 interfaces | 1 |
| Engineering software | STEP 7-Micro/WIN SMART |
| Firmware generation | 0AA1 hardware supports V2.7; no downgrade to V2.6 or earlier |
Features
Uses 24 V DC transistor outputs for fast switching applications.
Integrates Ethernet and RS485 communication for controller, HMI and serial-network duties.
Keeps program and data resources in a documented 20 KB memory allocation.
Compatibility
- Use a Micro/WIN SMART release that explicitly supports the 0AA1 V2.7 CPU generation.
- Verify 24 V DC supply capacity, commons, transistor-output load current and protective devices.
- Check the installed expansion modules, Ethernet addressing and RS485 parameters against the project.
- Do not substitute an SR relay-output CPU without reviewing supply and field-wiring design.
Replacement
- Archive the project, firmware version, communication settings, passwords and installed expansion list.
- Isolate controller and field power, identify every common and terminal and observe ESD handling.
- Restore only the approved project to a supported 0AA1 CPU and confirm module detection.
- Test transistor outputs under controlled conditions and validate all network and safety sequences.
FAQ
Q01
Can 6ES7288-1ST20-0AA1 use an older V2.6 firmware image?
No. Siemens states that 0AA1 CPUs cannot be downgraded to V2.6 or earlier.
Q02
What must be compared before replacing an ST20 with another S7-200 SMART CPU?
Compare the complete article number, supply type, I/O count and output technology, firmware generation, expansion needs and communications.
Q03
What should accompany a 6ES7288-1ST20-0AA1 enquiry?
Provide the complete label, Micro/WIN SMART project, firmware record, expansion list, IP settings and clear terminal photographs.
Q04
Why does the transistor-output identity matter for 6ES7288-1ST20-0AA1?
The 24 V DC transistor outputs differ from relay outputs in wiring, switching behavior and load compatibility.
Q05
What acceptance test is appropriate after CPU exchange?
Verify project checksum, communications, expansion modules, each affected input and output and the complete machine interlock sequence.
About IndustryParts
https://www.industryparts.com/Compact CPU requests keep the output technology explicit
IndustryParts records 6ES7288-1ST20-0AA1 with its 0AA1 firmware generation and DC/DC/DC architecture before preparing supply options.
- Exact ST20 identity retained
- Transistor outputs documented
- Firmware and project evidence reviewed
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