What Is the Allen-Bradley 1762-IQ8?
Downtime on a MicroLogix line often traces back to a failed or missing I/O slice. The Allen-Bradley 1762-IQ8 is a MicroLogix 1200 discrete input module that adds eight input channels in a single group to an existing controller. It is a single-slot width expansion module built by Rockwell Automation and sold under the Allen-Bradley brand.
This module accepts a nominal 24 VDC input and supports both sink and source wiring configurations. That flexibility matters when your field devices follow different grounding conventions. Instead of stocking two separate input cards, you keep one part on the shelf.
Technical Specifications That Matter
Three parameters drive most buying decisions for this module.
Input Voltage Range
The 1762-IQ8 operates across a 10-30 VDC input range. A 24 VDC nominal input sits comfortably inside that window, so standard industrial sensor and switch signals work without external conditioning.
ON-State and OFF-State Current
The module draws 2.0 mA minimum at 10 VDC, 8.0 mA nominal at 24 VDC, and 12.0 mA maximum at 30 VDC in the ON state. The OFF-state current stays at 1.5 mA or below. These thresholds tell you the module will reliably detect weak signals while rejecting leakage current that could cause false triggers.
Signal Delay and Isolation
Signal delay is 8 ms for both OFF-to-ON and ON-to-OFF transitions. For discrete sensing of pushbuttons, limit switches, and proximity sensors, that response time is more than adequate. The input group to backplane isolation is verified by dielectric tests of 1200 VAC for 1 second or 1697 VDC for 1 second, with a 75 VDC working voltage under IEC Class 2 reinforced insulation.
Backplane and Heat
The module draws 50 mA at 5.1 VDC from the backplane and 0 mA at 24 VDC. Heat dissipation is 3.7 Watts, which matters when you calculate enclosure thermal load.
Comparison With Similar Input Modules
| Feature | 1762-IQ8 | Typical 8-Channel DC Input Card |
|---|---|---|
| Channels | Eight (8) in one group | Eight (8) |
| Nominal input | 24 VDC | 24 VDC |
| Input range | 10-30 VDC | Varies by model |
| Sink/source support | Both | Often one only |
| Signal delay | 8 ms | Varies |
| Backplane draw | 50 mA at 5.1 VDC | Varies |
If your panel already runs MicroLogix hardware, the 1762-IQ8 avoids adapter plates and protocol converters that third-party cards may require.
Where the 1762-IQ8 Fits
Packaging and Material Handling
Conveyor zones use discrete inputs to detect package presence, jam conditions, and gate positions. Eight channels in one group cover a typical zone without wasting slots.
Panel Builder Retrofits
When a MicroLogix 1200 panel needs more discrete points, this module slides into the existing 1762 bus. No new power supply, no separate network drop.
Replacement and Upgrade Path
If a legacy input slice fails, the 1762-IQ8 is a direct expansion option for MicroLogix 1100, 1200, 1400, and 1500 controllers. Verify your controller’s hardware support before ordering, since the number of module instances depends on the host controller.
Installation Notes
Mount the module on a DIN rail or directly to a panel. Keep 50.8 cm (2 inches) of clearance on all sides for cooling airflow. The input terminal blocks include a finger-safe cover. Wire inputs to bit positions 0 through 7, and configure each channel after installation. Install in a non-hazardous, dry, clean environment with circuits that do not exceed Over Voltage Category II.
Maintenance and Reliability
Inspect terminal connections periodically and confirm the status LED indicates normal operation. The single status LED shows power and helps identify the module’s operational state. Remove power before servicing and prevent electrostatic discharge to avoid damage. Follow the manufacturer’s safety manual for all service work.
Selection Checklist
Before you buy, confirm your controller model, required channel count, and whether your field devices sink or source. The 1762-IQ8 covers both wiring styles. SpareTechPLC stocks industrial automation parts and can confirm current lifecycle status and availability for your application.
Frequently Asked Questions
Does the 1762-IQ8 work with a MicroLogix 1100?
Yes. The module is compatible with MicroLogix 1100, 1200, 1400, and 1500 controllers, though the number of module instances depends on the host controller’s hardware support.
Can I use both sinking and sourcing devices on the same module?
Yes. The 1762-IQ8 supports sink and source wiring configurations, so you can connect field devices referenced to either the negative or positive side of the power supply.
What is the signal delay on this module?
The signal delay is 8 ms for both OFF-to-ON and ON-to-OFF transitions.
How much backplane current does it draw?
The module draws 50 mA at 5.1 VDC and 0 mA at 24 VDC from the backplane.
What clearance does it need during mounting?
Allow 50.8 cm (2 inches) of clearance on all sides to maintain cooling airflow and ventilation.
