OMRON CP1W-8ER – 8-Point Relay Output I/O Expansion Unit | CP1 Series PLC Platform
Engineering Background
The OMRON CP1W-8ER is a relay output expansion unit designed for the CP1 series compact PLC platform — one of OMRON’s most widely deployed control architectures in discrete manufacturing, packaging, and building automation. As relay-based output modules remain the preferred interface for inductive loads, solenoids, and mixed-voltage field devices, the CP1W-8ER delivers robust, isolated switching without requiring external relay banks.
Product Positioning
Targeted at control engineers who need to expand the digital output capacity of CP1H or CP1L CPUs without migrating to a larger PLC chassis, the CP1W-8ER slots directly onto the CPU unit’s right-side expansion bus. It is the relay-output counterpart to the CP1W-8ET (transistor NPN) and CP1W-8ET1 (transistor PNP), and is selected when load isolation, AC switching capability, or mixed-voltage compatibility is required.
Complete Technical Specifications
| Model Number | CP1W-8ER |
| Manufacturer | OMRON Corporation (Japan) |
| Series / Platform | CP1 Series (CP1H / CP1L compatible) |
| Module Type | Digital Output Expansion Unit – Relay Contact |
| Output Points | 8 points |
| Output Type | Relay contact (NO) |
| Rated Load Voltage | 250 VAC / 24 VDC |
| Max Switching Current | 2 A per point |
| Max Switching Capacity | 500 VA (AC) / 48 W (DC) |
| Min Switching Load | 10 mA at 5 VDC |
| Relay Mechanical Life | 20,000,000 operations min. |
| Relay Electrical Life | 100,000 operations min. (rated load) |
| Output Response Time (ON) | 15 ms max. |
| Output Response Time (OFF) | 15 ms max. |
| Internal Current Consumption | 5 VDC, 0.036 A (from CPU bus) |
| Isolation | Photocoupler (CPU ↔ output circuit) |
| Indicators | Output status LED per point |
| Connection Method | Removable screw terminal block |
| Expansion Bus Interface | Right-side expansion connector (CP1 bus) |
| Max Expansion Units per CPU | Up to 3 units (CP1L) / up to 7 units (CP1H) |
| Dimensions (W × H × D) | 31 × 90 × 80 mm |
| Weight | Approx. 200 g |
| Operating Temperature | 0 to 55 °C |
| Storage Temperature | −20 to 70 °C |
| Operating Humidity | 10 to 90% RH (non-condensing) |
| Degree of Protection | IP20 |
| Applicable Standards | CE, UL, cUL, KC |
| Country of Origin | Japan |
| HS Code | 8537.10 |
Proven Application Environments
- Discrete Manufacturing: Conveyor line control, pneumatic valve actuation, motor starter interlocking
- Packaging Machinery: Sealer, labeler, and reject gate control with mixed AC/DC loads
- HVAC & Building Automation: Fan coil unit switching, damper actuator control, alarm output
- Food & Beverage: Washdown-adjacent panels where relay isolation prevents ground loop issues
- Water Treatment: Pump and valve sequencing with 24 VDC or 110/220 VAC field devices
- OEM Machine Builders: Compact panel designs requiring DIN-rail mounted CP1 expansion without external relay modules
Engineering Advantages
- Voltage-agnostic outputs: Switches both AC (up to 250 V) and DC loads from a single module — eliminates the need for separate relay banks when field devices operate at different voltages.
- True galvanic isolation: Relay contacts provide complete electrical isolation between the PLC logic bus and field wiring, protecting the CPU from inductive kickback and voltage transients.
- Plug-and-play expansion: Snaps directly onto the CP1H/CP1L CPU right-side bus — no additional power supply or backplane required; the CPU automatically recognizes the unit.
- Removable terminal block: Screw terminals can be disconnected without rewiring, enabling fast module swap during maintenance without disturbing field wiring.
- Per-point LED indicators: Immediate visual confirmation of output state during commissioning and fault diagnosis.
- Compact DIN-rail footprint: 31 mm wide — 8 output points in a minimal panel footprint, preserving enclosure space for other components.
System Architecture & Signal Flow
The CP1W-8ER connects to the right-side expansion port of a CP1H or CP1L CPU unit. The CPU allocates output words to the expansion unit automatically based on slot position. Signal flow is as follows:
- PLC Program → CPU Output Image: Ladder/ST program sets output bits in the CPU’s I/O image table.
- CPU Bus → Expansion Unit: Output data is transferred via the internal CP1 expansion bus at each scan cycle.
- Photocoupler Isolation Stage: Output signals pass through optocouplers, isolating logic-level signals from relay coil drive circuits.
- Relay Coil Energization: Each output bit energizes the corresponding relay coil, closing the NO contact.
- Field Load Switching: The closed relay contact completes the field circuit, switching the connected load (solenoid, contactor coil, indicator lamp, etc.).
Compatible CPUs: CP1H-X40DR-A, CP1H-XA40DR-A, CP1H-Y20DT-D, CP1L-M60DR-A, CP1L-M30DR-A, CP1L-L20DR-A, and all CP1H/CP1L relay-output CPU variants.
Sourcing & Quality Verification
- OEM Origin: All units sourced from authorized OMRON distribution channels or verified surplus with full traceability documentation.
- Pre-shipment Inspection: Each unit undergoes visual inspection, label verification (date code, lot number, country of origin), and continuity check before dispatch.
- Authenticity Indicators: Genuine CP1W-8ER units feature OMRON holographic labels, laser-etched model/serial numbers, and consistent terminal block construction. Counterfeit risk is mitigated through our supplier qualification process.
- Condition: New-in-box (NIB) unless explicitly stated as tested-used or refurbished in the listing variant.
- Documentation: OMRON datasheet and CE/UL declaration of conformity available upon request.
Procurement Process
- Confirm compatibility: Verify your CPU model (CP1H or CP1L) and available expansion slots. CP1L-L CPUs support up to 3 expansion units; CP1H CPUs support up to 7.
- Quantity & lead time: Contact us for volume pricing (>5 units) or expedited shipping options. Most in-stock orders ship within 1–2 business days.
- Place order: Add to cart and complete checkout. We accept T/T bank transfer, PayPal, and major credit cards.
- Shipping & customs: International orders ship via DHL/FedEx with full commercial invoice and HS code 8537.10 declared. Import duties are the buyer’s responsibility.
- After-sales support: 12-month warranty against manufacturing defects. Contact support@konmask.com for RMA or technical queries.
Technical FAQ
Q: Can the CP1W-8ER switch 220 VAC loads directly?
A: Yes. The relay contacts are rated for 250 VAC / 2 A, making them suitable for switching 110 VAC and 220 VAC loads within the rated current.
Q: Does the CP1W-8ER require an external power supply?
A: No. It draws 5 VDC (36 mA) directly from the CP1 CPU expansion bus. No separate power supply is needed for the module itself; field load power is supplied externally as required by the application.
Q: How many CP1W-8ER units can I connect to one CP1L-M30DR-A?
A: The CP1L-M series supports up to 3 expansion units. You can connect up to 3 × CP1W-8ER for a total of 24 additional relay outputs.
Q: What is the I/O address allocation for the CP1W-8ER?
A: The CPU automatically assigns output words based on expansion slot position (left to right). The first expansion unit occupies the next available output word after the CPU’s built-in outputs. Refer to OMRON W462-E1 (CP1L Operation Manual) or W451-E1 (CP1H) for detailed I/O allocation tables.
Q: Is the CP1W-8ER compatible with CX-Programmer?
A: Yes. CX-Programmer automatically detects connected expansion units when the PLC is online. No additional configuration is required for I/O allocation.
Q: What is the difference between CP1W-8ER and CP1W-8ET?
A: CP1W-8ER uses relay contacts (suitable for AC/DC, higher current, slower response ~15 ms). CP1W-8ET uses NPN transistor outputs (DC only, lower current, faster response ~0.1 ms). Choose relay for inductive/AC loads; choose transistor for high-speed or DC-only applications.
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