Allen-Bradley 1790-0W8X: Simple & Reliable 8-Channel Relay Output

Add flexible switching power to your control system. The Allen-Bradley 1790-0W8X gives you eight isolated relay outputs. This compact module lets you control motors, lights, and solenoids directly. It connects easily to your PLC for expanded control capabilities.

Why You Need This Output Module

• Universal Load Control: Switch both DC (5-24V) and AC (30V) loads with the same module.
• Clear Visual Feedback: Eight green LEDs show the status of each output at a glance.
• Easy to Install: Simple DIN-rail mounting and a single 37-pin connector for all wiring.
• Strong Electrical Protection: High isolation (1250V AC) protects your controller from field-side noise.

Key Technical Specifications

• Product Model: Allen-Bradley 1790-0W8X (1790 Series Compact I/O).
• Relay Configuration: 8 Form A (SPST-NO) relays.
• Switching Capacity: 2.0 A @ 24V DC or 30V AC.
• Contact Life: 300,000 cycles (resistive), 100,000 cycles (inductive).
• Response Speed: Turn ON/OFF delay less than 10 milliseconds each.
• Power Supply: 24V DC (19.2-28.8V) field power required.
• Isolation Rating: 1250V AC RMS between I/O and control logic.
• On-State Loss: Low voltage drop, max 0.5V at full load.

Installation & Wiring Details

• Connection Interface: Single 37-pin D-sub connector for fast, organized wiring.
• Mounting: Standard 35mm DIN rail mounting.
• Minimum Load: Requires at least 100 µA / 100 mV DC for reliable contact wetting.
• Power Consumption: Low, only about 10 mA per active channel.

What's Included & Support

• You receive one 1790-0W8X output module ready for installation.
• This product is covered by a 12-month warranty from the date of purchase.
• We ship quickly worldwide using FedEx, UPS, and DHL.

Expert FAQs

• Can I use this to directly start a small 24V DC motor?
  Yes. Each relay can handle 2A, suitable for many small motors. Always check the motor's inrush current, which can be much higher than its running current, to ensure it doesn't exceed the relay rating.
• What does "Form A" mean for the relay contacts?
  Form A means Single-Pole, Single-Throw, Normally Open (SPST-NO). The contacts are open when the relay is off and close to complete the circuit when the relay is energized.
• Why is there a minimum load requirement (100µA)?
  This ensures enough current flows to keep the relay contacts clean and free from oxidation buildup, which can cause high resistance or failure over time. It's called "contact wetting."
• Is it suitable for switching AC and DC on the same module?
  Yes, the relays are agnostic to current type. However, you must ensure the voltage (DC or AC peak) for any channel does not exceed the 30V maximum rating.
• How do I protect the relays when switching inductive loads like solenoid coils?
  Always use a suppression device like a flyback diode (for DC) or a snubber circuit (for AC) across the inductive load. This protects the relay contacts from voltage spikes that occur when the circuit opens, greatly extending contact life.

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