When a Packaging Line Needed More AC Outputs
A plant engineer faced a familiar problem: the SLC 500 chassis was full, yet the packaging line still needed sixteen discrete AC outputs to drive indicator lamps, solenoids, and motor starters. Every added relay panel meant more wiring, more cabinet space, and more failure points. The Allen-Bradley 1746-OA16 solved that challenge in a single slot. This SLC 500 digital AC output module packs sixteen outputs into two groups of eight, delivering 120/240 VAC nominal signals across an 85-264 VAC operating range. For facilities running legacy SLC 500 systems, it remains a practical way to expand control without rebuilding the architecture.
What the 1746-OA16 Delivers
Rockwell Automation designed this module for general-purpose applications. Each output group carries eight channels, and the module consumes 16-bit I/O memory. The removable terminal blocks let technicians swap a module without disconnecting field wiring, which shortens replacement time during unplanned downtime. Filter circuitry and optical coupling reduce signal noise, while LED indicators show output status for faster troubleshooting. Output values are accessible through Ladder Logic, so existing SLC 500 programs integrate the module without special configuration.
Key Specifications at a Glance
Output Capacity and Voltage
The 1746-OA16 provides sixteen outputs rated for 120/240 VAC nominal voltage, with an operating range of 85-264 VAC. Continuous current per point reaches 0.50 A at 30 °C (86 °F) and 0.25 A at 60 °C (140 °F). Per module, the maximum continuous current is 8.0 A at 30 °C (86 °F) and 4.0 A at 60 °C (140 °F).
Switching Behavior
OFF-to-ON delay is 11.0 ms, while ON-to-OFF delay is 1 ms. OFF-state leakage current is 2 mA, and load current is 10 mA. These values matter when outputs drive sensitive loads or when timing affects machine sequencing.
Power and Environmental Limits
Backplane current draw at 5.1 V is 0.370 A. The module operates between 32 and 140 °F (0 to 60 °C) with 5 to 95% noncondensing relative humidity.
Where This Module Fits Best
Packaging and Material Handling
Indicator lamps, diverters, and small solenoids run well within the 0.50 A per-point rating at 30 °C. The 85-264 VAC range accepts standard plant AC without external conversion.
Legacy SLC 500 Upgrades
When a line needs more AC outputs but the chassis has open slots, the 1746-OA16 adds sixteen channels without a separate relay panel. This approach saves cabinet space and wiring labor.
Mixed I/O Architectures
The SLC 500 platform supports combinations of digital and analog I/O. This module installs as local or remote I/O with SLC 500 processors, CompactLogix, and ControlLogix controllers, provided the power supply can supply the required current for every module in the chassis.
Installation and Replacement Notes
Install the module in any open single slot of the SLC 500 chassis. Confirm the backplane power budget before adding modules, since each unit draws 0.370 A at 5.1 V. Use the removable terminal blocks to pre-wire field connections, then seat the module. Follow the manufacturer’s safety manual for all wiring and configuration. Verify current lifecycle status and availability with SpareTechPLC before ordering.
Maintenance and Long-Term Reliability
Inspect terminal connections periodically for tightness and signs of heat. Keep the enclosure within the 32 to 140 °F operating range and maintain humidity below 95% noncondensing. LED indicators simplify output verification during routine checks. Because the module uses optical coupling and filter circuitry, it resists electrical noise common in industrial cabinets. For plants running SLC 500 systems, keeping spare 1746-OA16 modules on hand reduces downtime risk when an output channel fails.
Compatibility and Integration
The 1746-OA16 works with SLC 500 programmable logic controllers as local or remote I/O. It also integrates with CompactLogix and ControlLogix programmable automation controllers. There is no limit to how many modules you can install, as long as the system power supply meets the total current demand. Ladder Logic programs access output values directly, so no special software blocks are required.
Buyer’s Checklist Before You Order
Confirm your chassis has an open slot and sufficient backplane current. Verify that your loads stay within 0.50 A per point at 30 °C or 0.25 A at 60 °C. Check that your field voltage falls between 85 and 264 VAC. If you need removable terminal blocks for fast swaps, this module includes them. SpareTechPLC stocks industrial automation parts and can confirm compatibility with your existing SLC 500 hardware.
Frequently Asked Questions
How many outputs does the 1746-OA16 provide?
It provides sixteen AC outputs arranged in two groups of eight channels each.
What voltage range does this module accept?
The operating voltage range is 85-264 VAC with a nominal output of 120/240 VAC.
Can I use this module with CompactLogix controllers?
Yes. It installs as local or remote I/O with SLC 500 processors, CompactLogix, and ControlLogix controllers.
What is the maximum current per output point?
Each point carries 0.50 A at 30 °C (86 °F) and 0.25 A at 60 °C (140 °F).
Does the module include removable terminal blocks?
Yes. Removable terminal blocks allow module replacement without disconnecting field wiring.
