Product Overview
Downtime on a legacy SLC 500 line often traces back to a single failed output card. The Allen-Bradley 1746-OA16 solves that problem directly. It is a digital AC output module from the SLC 500 series, built by Allen-Bradley and manufactured by Rockwell Automation. The module delivers sixteen AC output channels arranged in two groups of eight. Each channel switches 120/240 VAC nominal signals across an operating voltage range of 85-264 VAC. When a plant needs to drive AC relays, solenoids, or indicator banks from an existing SLC 500 chassis, this module is the practical drop-in answer.
Key Parameters That Matter on the Floor
Output Capacity and Grouping
Sixteen outputs in two isolated groups of eight give technicians flexibility during wiring and fault isolation. One group can fail without taking down the other. Each point carries 0.50 A at 30 °C and 0.25 A at 60 °C. The module itself handles a maximum of 8.0 A at 30 °C and 4.0 A at 60 °C. Engineers should total their load currents before populating a chassis.
Switching Speed
The 1746-OA16 turns ON in 1 ms and turns OFF in 11.0 ms. That asymmetry matters in applications where fast energizing is critical but slower de-energizing is acceptable. OFF-state leakage current sits at 2 mA, so sensitive loads should be reviewed against that figure.
Backplane and Memory Load
The module draws 0.370 A from the 5.1 V backplane supply and occupies 16-bit I/O memory in a single chassis slot. Power budgeting across the rack is therefore straightforward to calculate.
Signal Integrity Features
Filter circuitry and optical coupling reduce electrical noise on the output side. This protects the controller from transients generated by inductive AC loads.
Where the 1746-OA16 Fits Best
Replacing Obsolete Output Cards
Plants running SLC 500 systems frequently face end-of-life pressure on I/O hardware. The 1746-OA16 is a direct replacement path for failed AC output modules in the same family. Because it uses removable terminal blocks, technicians swap the card without disconnecting field wiring. That single feature can cut replacement time from hours to minutes.
Driving AC Pilot Devices
Stack lights, horns, and AC contactors are common loads. The 85-264 VAC range covers both 120 V and 240 V installations, so one spare part serves multiple machine types across a facility.
Mixed I/O Chassis
The SLC 500 platform shares a common hardware base across digital and analog modules. A single chassis can combine the 1746-OA16 with analog cards, saving panel space and cost compared with separate remote racks.
Installation and Setup Guidance
Mount the module in any free single slot of an SLC 500 chassis. Confirm the power supply can deliver the backplane current required by every installed module. Wire field devices to the removable terminal blocks, keeping the two output groups separated where circuit isolation is needed. Verify load current per point stays within the 30 °C and 60 °C ratings for the actual panel temperature. Use the LED indicators to confirm output state during commissioning.
Maintenance and Reliability
Inspect terminal block connections periodically for looseness caused by thermal cycling. Keep the enclosure within the 0 to 60 °C operating range and 5 to 95% noncondensing humidity. Dust buildup on the card edge can affect seating, so follow your site’s standard panel cleaning schedule. LED status indicators simplify fault tracing when an output stops responding.
Compatibility and Integration
The 1746-OA16 works as local or remote I/O with any SLC 500 processor. It also integrates with CompactLogix and ControlLogix programmable automation controllers. Output values are accessible through Ladder Logic, so existing programs need minimal adjustment. There is no fixed limit on how many modules can be installed, provided the power supply supports the total current draw.
Selection Checklist Before You Buy
Confirm your chassis has an open slot and adequate backplane capacity. Verify the load voltage falls within 85-264 VAC. Check that per-point and per-module current demands match your panel’s ambient temperature. Buyers seeking genuine Allen-Bradley SLC 500 hardware can source the 1746-OA16 through SpareTechPLC, which stocks industrial automation parts and publishes related news.
Frequently Asked Questions
How many outputs does the 1746-OA16 provide?
It provides sixteen AC outputs, split into two groups of eight channels each.
What voltage range does this module accept?
The operating voltage range is 85-264 VAC, with 120/240 VAC nominal output.
Can I replace the module without rewiring?
Yes. Removable terminal blocks let you swap the card while field wiring stays connected.
What is the maximum current per output point?
Each point carries 0.50 A at 30 °C and 0.25 A at 60 °C.
Which controllers support this module?
SLC 500 processors support it directly, and it also works with CompactLogix and ControlLogix PACs.
