Siemens 6ES7288-2DR08-0AA0 – 8-Point Relay Digital Output Module | S7-200 SMART Platform
Engineering Background
The Siemens S7-200 SMART series is Siemens’ purpose-built compact PLC platform for cost-sensitive yet performance-demanding OEM and machine-builder applications across Asia-Pacific markets. Designed as the successor to the legacy S7-200, the SMART line retains the familiar STEP 7-Micro/WIN SMART programming environment while delivering enhanced Ethernet connectivity, expanded I/O expansion capability, and improved cycle-time performance.
Product Positioning
The 6ES7288-2DR08-0AA0 is a dedicated 8-channel relay digital output expansion module for the S7-200 SMART CPU family. Its relay contact outputs provide galvanic isolation between PLC logic and field devices, making it the preferred choice for controlling AC loads, solenoid valves, motor starters, and mixed-voltage actuators where transistor outputs are unsuitable. Procurement engineers specify this module when load-side voltage flexibility and robust isolation are non-negotiable requirements.
Complete Technical Specifications
| Part Number / SKU | 6ES7288-2DR08-0AA0 |
| Module Type | Digital Output Module – Relay (DO) |
| Compatible Platform | Siemens S7-200 SMART |
| Number of Outputs | 8 DO (Relay) |
| Output Type | Relay contact (Form A – NO) |
| Rated Load Voltage | 24 VDC / 5–250 VAC |
| Max Switching Current | 2 A per point |
| Max Simultaneous Outputs | 8 (all simultaneously active) |
| Isolation | Galvanic isolation – relay contact between logic and field |
| Output Groups | 2 groups (4 points per common) |
| Mechanical Relay Life | 10,000,000 operations (no load) |
| Electrical Relay Life | 100,000 operations (rated load) |
| Logic Supply Voltage | 24 VDC (from CPU expansion bus) |
| Current Consumption (5 VDC bus) | ≤ 40 mA |
| Current Consumption (24 VDC) | ≤ 80 mA |
| Operating Temperature | 0 °C to +55 °C |
| Storage Temperature | −40 °C to +70 °C |
| Relative Humidity | 5% to 95% (non-condensing) |
| Degree of Protection | IP20 |
| Dimensions (W × H × D) | 45 mm × 100 mm × 81 mm |
| Weight | Approx. 160 g |
| Mounting | DIN rail (EN 60715 – 35 mm) |
| Certifications | CE, UL, cUL, FM, ATEX Zone 2 |
| MLFB / Order Number | 6ES7288-2DR08-0AA0 |
Proven Application Environments
- Conveyor & Material Handling: Relay outputs switch motor contactors and solenoid brakes at mixed AC/DC voltages without additional interface relays.
- Packaging Machinery: Controls pneumatic valve banks and reject gates where 24 VDC transistor outputs cannot drive inductive AC coils directly.
- HVAC & Building Automation: Switches fan starters, damper actuators, and pump contactors at 220 VAC without external relay panels.
- Water Treatment & Pumping Stations: Drives submersible pump contactors and dosing valve solenoids in wet-area control panels.
- Textile & Printing Equipment: Interfaces with legacy AC-powered actuators common in older machine retrofits.
- Food & Beverage Processing: Controls washdown-rated solenoid valves and conveyor drives in hygienic environments.
Engineering Advantages
- Galvanic Isolation: Relay contacts provide complete electrical isolation between PLC logic (24 VDC) and field-side loads (up to 250 VAC), eliminating ground loop interference and protecting the CPU from field-side transients.
- Voltage Flexibility: A single module simultaneously switches 24 VDC solenoids and 220 VAC contactors across different output groups — reducing BOM complexity.
- Plug-and-Play Expansion: Connects directly to the S7-200 SMART CPU expansion bus via the integrated ribbon connector — no additional power supply or backplane required for logic power.
- Compact DIN-Rail Form Factor: 45 mm width minimizes panel real estate; compatible with standard 35 mm DIN rail for rapid installation.
- High Mechanical Endurance: 10 million mechanical operations ensure long service life in high-cycle applications.
- Siemens TIA Ecosystem: Fully supported by STEP 7-Micro/WIN SMART V2.x; I/O addresses auto-assigned during CPU configuration.
System Architecture & Signal Flow
The 6ES7288-2DR08-0AA0 connects to the right side of the S7-200 SMART CPU (or preceding expansion module) via the integrated expansion bus connector. The CPU allocates 8 output bits (1 byte) to this module in the process image output (PQ) area. During each CPU scan cycle, the output image is transferred to the module, which energizes or de-energizes the corresponding relay coils. Each relay coil drives a Form-A (NO) contact rated at 2 A. Two independent common terminals allow different load voltages per group of 4 outputs.
Expansion chain limit: Up to 6 expansion modules per S7-200 SMART CPU (subject to CPU model power budget).
Sourcing & Quality Verification
- All units sourced through authorized Siemens distribution channels or verified surplus with full traceability documentation.
- Each module inspected for: intact holographic label, correct MLFB string, firmware version compatibility, and physical condition prior to dispatch.
- Batch certificates and country-of-origin documentation available upon request for customs and compliance purposes.
- Counterfeit risk mitigation: Konmask.com performs label authentication and functional verification on all Siemens modules before listing.
Procurement Process
- Confirm Compatibility: Verify your S7-200 SMART CPU model and available expansion bus slots / power budget.
- Request Quote: Contact support@konmask.com for volume pricing, lead time, and availability confirmation.
- Place Order: Add to cart and complete checkout, or submit a PO via email for B2B net-terms orders.
- Shipping: Standard DHL/FedEx international express (3–7 business days); sea freight available for bulk orders.
- Documentation: Commercial invoice, packing list, and CE declaration of conformity included with every shipment.
Technical FAQ
Q: Can I mix relay and transistor output modules on the same S7-200 SMART CPU?
A: Yes. The S7-200 SMART expansion bus supports mixing of digital input, digital output (relay or transistor), and analog modules in any order, subject to the total expansion module count and power budget of the CPU.
Q: What is the maximum inrush current the relay contacts can handle?
A: The relay contacts are rated for 2 A continuous. For inductive loads, ensure the steady-state current is within this limit; use external surge suppressors (RC snubbers or varistors) across inductive loads to extend relay life.
Q: Is the 6ES7288-2DR08-0AA0 compatible with S7-200 (classic) CPUs?
A: No. This module is designed exclusively for the S7-200 SMART platform. It is not electrically or mechanically compatible with the legacy S7-200 (6ES7 21x series) CPUs.
Q: How are output addresses assigned in STEP 7-Micro/WIN SMART?
A: Output addresses are automatically assigned based on the module’s position in the expansion chain. The first expansion module’s outputs begin at QB0 (or the next available byte after the CPU’s onboard outputs). Refer to the system manual for address mapping tables.
Q: What programming software is required?
A: STEP 7-Micro/WIN SMART V2.3 or later (free download from Siemens Industry Online Support). No additional hardware configuration tool is required — the module is auto-detected by the CPU.
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