SIEMENS 6ES7288-1SR40-0AA0 CPU SR40 | Replacement, Equivalent & Selection Guide
The SIEMENS 6ES7288-1SR40-0AA0 is a standard CPU module in the S7-200 SMART series, featuring 24 digital inputs and 16 relay outputs (40 I/O total). Designed for compact automation tasks in manufacturing, HVAC, packaging, and process control, this relay-output CPU is widely deployed across Asia-Pacific industrial sites. Whether you need an original unit, a verified equivalent, or a compatible replacement, this guide covers everything you need to make the right selection.
Technical Specifications
- Model: 6ES7288-1SR40-0AA0
- Series: SIMATIC S7-200 SMART
- CPU Type: SR40 (Standard Relay Output)
- Digital Inputs: 24 × DC 24V
- Digital Outputs: 16 × Relay (2A per point)
- Total I/O: 40 onboard
- Max Expandable I/O: Up to 188 points (with expansion modules)
- Program Memory: 24 KB
- Data Memory: 10 KB (retentive)
- Communication Ports: 1 × Ethernet (RJ45), 1 × RS485
- Ethernet Protocol: PROFINET, Modbus TCP, S7 Protocol
- Power Supply: AC 85–264V / DC 24V (dual-power version)
- Operating Temperature: 0°C to +55°C
- Protection Rating: IP20
- Dimensions (W×H×D): 175 × 100 × 81 mm
- Weight: ~240 g
- Programming Software: STEP 7-Micro/WIN SMART
- Certifications: CE, UL, cUL
Compatible Replacement & Equivalent Models
The following models are functionally equivalent or drop-in replacements for the 6ES7288-1SR40-0AA0 in most applications. Always verify I/O count, output type, and communication requirements before substituting.
- 6ES7288-1SR40-0AA1 – Revised hardware revision of the same SR40; fully compatible firmware and wiring.
- 6ES7288-1ST40-0AA0 (ST40) – Transistor output variant; same 24DI/16DO count. Use when high-speed output or PWM is required instead of relay.
- 6ES7288-1SR30-0AA0 (SR30) – Smaller relay CPU (18DI/12DO); suitable if I/O count can be reduced with expansion modules.
- 6ES7288-1SR60-0AA0 (SR60) – Larger relay CPU (36DI/24DO); use when additional onboard I/O is needed without expansion.
- 6ES7212-1BE40-0XB0 (S7-1200 CPU 1212C) – Cross-series upgrade path; offers IEC 61131-3 programming and TIA Portal integration for future-proof projects.
Note: Cross-series replacements (S7-1200) require program migration and are not pin-compatible. Consult Konmask technical support for migration assistance.
Why Choose the Original Model
- Proven Reliability: S7-200 SMART CPUs are deployed in millions of machines globally with MTBF exceeding 100,000 hours.
- Relay Output Durability: Relay contacts rated for 100,000 mechanical operations — ideal for inductive loads, motors, and solenoids.
- Integrated Ethernet: Built-in RJ45 port eliminates the need for a separate communication module, reducing BOM cost.
- STEP 7-Micro/WIN SMART: Free programming software with motion control wizards, PID auto-tune, and HMI configuration tools.
- Compact Footprint: DIN-rail mount with minimal panel space — ideal for retrofit and space-constrained enclosures.
- Long-term Availability: Konmask maintains stock of both current production and legacy S7-200 SMART modules to support installed base maintenance.
Typical Applications
- Conveyor and material handling systems
- HVAC and building automation (fan, pump, valve control)
- Packaging and labeling machines
- Water treatment and pump station control
- Injection molding auxiliary equipment
- Small-scale process control and batch systems
- OEM machine builders requiring compact, cost-effective PLC solutions
System Compatibility
- Expansion Modules: Compatible with all 6ES7288-2xx and 6ES7288-3xx expansion modules (digital, analog, RTD, thermocouple)
- Signal Boards: Supports 6ES7288-5xx signal boards for additional analog or digital I/O without expansion rail
- HMI Panels: Direct connection to SIMATIC Smart Line panels (6AV6648-xxxx) via Ethernet or RS485
- SCADA/DCS: Modbus TCP and S7 protocol support enables integration with WinCC, iFIX, InTouch, and third-party SCADA systems
- Drives: Compatible with SINAMICS V20, G120 via USS/Modbus RTU over RS485
- Programming Environment: STEP 7-Micro/WIN SMART V2.4 and above (Windows 7/10/11)
Selection Guide
Use the table below to select the correct S7-200 SMART CPU for your application:
| Model | DI | DO | Output Type | Best For |
|---|---|---|---|---|
| SR20 (6ES7288-1SR20-0AA0) | 12 | 8 | Relay | Small machines, low I/O |
| SR30 (6ES7288-1SR30-0AA0) | 18 | 12 | Relay | Mid-size relay control |
| SR40 (6ES7288-1SR40-0AA0) | 24 | 16 | Relay | Standard relay applications ✓ |
| SR60 (6ES7288-1SR60-0AA0) | 36 | 24 | Relay | High I/O relay control |
| ST20 (6ES7288-1ST20-0AA0) | 12 | 8 | Transistor | High-speed, PWM output |
| ST30 (6ES7288-1ST30-0AA0) | 18 | 12 | Transistor | Servo/stepper positioning |
| ST40 (6ES7288-1ST40-0AA0) | 24 | 16 | Transistor | High-speed equivalent of SR40 |
| ST60 (6ES7288-1ST60-0AA0) | 36 | 24 | Transistor | High I/O transistor control |
Key Decision Points:
- Choose Relay (SR) for inductive loads, motors, solenoids, and AC output circuits.
- Choose Transistor (ST) for high-speed counting, PWM, or servo/stepper pulse output.
- Add expansion modules if onboard I/O is insufficient — up to 6 expansion modules supported.
Quality Assurance & Sourcing
- Authorized Distribution: Konmask sources 6ES7288-1SR40-0AA0 units from verified Siemens-authorized channels and bonded warehouses.
- Authenticity Verification: Every unit includes original Siemens holographic label, factory serial number, and CE/UL markings. Counterfeit detection checks performed on all incoming stock.
- Condition Options: New-in-box (NIB), factory-refurbished, and tested-used units available — clearly labeled at time of quotation.
- Warranty: 12-month warranty on new units; 90-day warranty on refurbished/used units.
- Traceability: Full lot traceability with certificate of conformance available on request.
- Export Compliance: Units shipped with proper HS code documentation (HS: 8537.10) for customs clearance.
How to Order
-
Confirm Part Number: Verify the full model number on your existing unit or engineering BOM:
6ES7288-1SR40-0AA0 - Specify Quantity & Condition: Indicate required quantity and whether new, refurbished, or used is acceptable.
- Request a Quote: Contact us via the form below, email, or phone for pricing and lead time.
- Review Proforma Invoice: We issue a proforma invoice with unit price, shipping cost, and estimated delivery.
- Payment & Dispatch: Payment via T/T, PayPal, or trade terms (for approved accounts). Units dispatched within 1–3 business days of payment confirmation.
- Shipping & Tracking: DHL, FedEx, or SF Express with full tracking. Export documentation included.
Replacement & Compatibility FAQ
Q: Can I replace 6ES7288-1SR40-0AA0 with 6ES7288-1SR40-0AA1?
A: Yes. The AA1 is a hardware revision of the same model. It is fully software- and wiring-compatible with no program changes required.
Q: Can I use the ST40 (transistor) as a direct replacement for the SR40 (relay)?
A: The I/O count is identical, but output wiring differs. Relay outputs are normally-open dry contacts; transistor outputs are NPN/PNP sourcing/sinking. Rewiring and output circuit review are required.
Q: Is the S7-200 SMART compatible with TIA Portal?
A: No. S7-200 SMART uses STEP 7-Micro/WIN SMART exclusively. TIA Portal is for S7-1200/1500 series. If TIA Portal is required, consider migrating to S7-1200.
Q: Can I expand the SR40 with analog modules?
A: Yes. The SR40 supports up to 6 expansion modules including analog input (6ES7288-3AE04), analog output (6ES7288-3AQ02), and RTD/thermocouple modules.
Q: What is the lead time for 6ES7288-1SR40-0AA0?
A: In-stock units ship within 1–3 business days. For large quantities or special requirements, contact us for a confirmed lead time.
Q: Do you provide a certificate of origin or conformance?
A: Yes. Certificate of conformance and country of origin documentation are available on request for all new units.
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