The Allen-Bradley 1791-OA16 delivers sixteen digital AC outputs in two isolated groups of eight channels each. Each group handles up to 300 mA continuously under proper mounting conditions. This module supports an operating voltage range of 20-132VAC at 47-63 Hz.
Many industrial applications use the 1791-OA16 to drive pilot lamps, buzzers, relays, contactors, and small solenoids. Because it mounts directly near the load, you avoid long signal cable runs. Consequently, this reduces installation costs and improves system reliability.
The module requires an external power supply of 85-132VAC at 150 mA. It provides isolation ratings of 500VAC between power and RIO, plus 1250VAC between I/O groups and logic. Therefore, noise and ground loop issues stay minimal.
The 1791-OA16 has a nominal output voltage of 120VAC. Its ON-state minimum current is 50 mA per channel, with a maximum voltage drop of 1.5V peak at 300 mA. Off-state leakage current is only 3 mA, which prevents false triggering on sensitive loads.
Output delay times are critical for timing-sensitive processes. The OFF-to-ON delay is 1.0 ms at both 50 Hz and 60 Hz. The ON-to-OFF delay measures 8.3 ms at 60 Hz or 10.0 ms at 50 Hz. Additionally, surge current reaches 10 A for 50 ms per output, repeatable every 2 seconds.
For diagnostics, a built-in status indicator helps troubleshoot field wiring and module health. The terminal strip is removable, which simplifies replacement and wiring changes.
You can mount the 1791-OA16 vertically or horizontally. However, current ratings depend on orientation and temperature.
Vertical mounting: 600 mA per output at 30°C, derated to 300 mA at 60°C.
Horizontal mounting: 300 mA per output at 30°C, derated to 150 mA at 60°C.
Use 14 AWG stranded wire with a maximum insulation thickness of 3/64 inches. The module weighs only 0.54 kg, so it fits easily in small enclosures.
Before installing the 1791-OA16, verify compatibility with your PLC system. This module works with PLC-2, PLC-3, PLC-5/20, and PLC-5 controllers. Next, consider the number of blocks, throughput needs, total cable distance, and transmission rate.
Mount the module near your AC loads to keep field wiring short. Connect external power between 85-132VAC at 47-63 Hz. Then attach the removable terminal strip and secure all wires. Finally, check that each output drives at least 50 mA to stay within specification.
1791-OA16 module – 1 unit
Removable terminal strip – 1 piece
Installation instructions leaflet – 1 copy
Note: No certificates or warranty documents are included. Certificates and warranty are handled separately by your supplier.
We ship worldwide using Fedex, UPS, or DHL. Tracking numbers are provided within 24 hours after dispatch.
1. Can the 1791-OA16 drive a small contactor directly?
Yes, it can. The minimum ON-state current is 50 mA, and the maximum continuous current depends on mounting orientation. For vertical mounting at 30°C, you get 600 mA per channel, which easily operates most small contactors.
2. What happens if I connect a load below 50 mA?
The module may not turn off completely because the off-state leakage is 3 mA. For very light loads like LEDs, add a bleeder resistor to ensure the output drops below the holding current.
3. Is the 1791-OA16 compatible with modern ControlLogix?
Not directly. This module uses the legacy block I/O protocol designed for PLC-2, PLC-3, and PLC-5 systems. For ControlLogix, you would need a 1771 or 1794 adapter, but native compatibility is not available.
4. How do I replace a faulty 1791-OA16 without rewiring everything?
The removable terminal strip lets you disconnect all field wires in one piece. Simply unscrew the terminal block from the old module, then attach it to the new 1791-OA16. This keeps wiring identical and saves time.
5. Why does the ON-to-OFF delay differ between 50 Hz and 60 Hz?
The module synchronizes output turn-off with the AC line cycle. At 60 Hz, one cycle takes 16.6 ms, so the module waits half a cycle (8.3 ms). At 50 Hz, half a cycle takes 10 ms. This design reduces contact arcing and extends relay life.
| Brand Name | Allen‑Bradley |
| Model No. | 1791-0A16 |
| Product Type | Digital AC Output Module |
| hasMerchantReturnPolicy | Adjust according to reality |
| Shippingdetails | Adjust according to reality |
