Product Description: Allen‑Bradley 1791‑8AC Block I/O
The 1791‑8AC is a distributed block I/O module from the Allen‑Bradley 1791 series. It provides 8 AC inputs and 8 AC outputs at 120 VAC. This module acts as a RIO adapter for legacy PLC‑2, PLC‑3, PLC‑5, and SLC‑500 with 1747‑SN scanners. It uses a daisy‑chain topology over Belden 9463 cable. The embedded RIO interface handles input updates and output commands. It is ideal for remote I/O architectures in industrial control.
Key Technical Specifications
| Brand | Allen‑Bradley (Rockwell Automation) |
| Model | 1791‑8AC |
| Series | 1791 Block I/O |
| I/O Configuration | 8 inputs / 8 outputs (120 VAC) |
| Input ON voltage | 79‑132 VAC (5 mA min @79V) |
| Input OFF voltage | ≤35 VAC (2.3 mA max) |
| Output voltage range | 20‑132 VAC |
| Output current (vertical) | 300‑600 mA @ 30‑60 °C |
| Output current (horizontal) | 150‑300 mA @ 30‑60 °C |
| External power | 85‑132 VAC, 150 mA |
| Power dissipation | 12.9 W max |
| Thermal dissipation | 43.99 BTU/hr |
| Isolation | 500 VAC (tested 1250 VAC) |
| Surge current | 10 A for 50 ms, 2 s rep. |
| Mounting | Vertical / Horizontal |
| Weight | 0.94 lbs (0.43 kg) |
| Dimensions | 176.5 x 68.8 x 98 mm |
Installation & Environmental
- Vertical or horizontal mounting with derating curves
- Ambient temperature range: 0‑60 °C (operational)
- Storage temperature: ‑40 to +85 °C
- Humidity: 5‑95% non‑condensing
- Vibration: 2 G @ 10‑500 Hz per IEC 60068
- Shock: 30 G (11 ms pulse)
- EMI immunity: meets IEC 61000‑6‑2
Diagnostics & Communication
- Built‑in RIO adapter with block transfer (BTR/BTW)
- Supports up to 32 words read/write in parallel
- Output delay: 8.3 ms (OFF→ON), 1 ms (ON→OFF)
- Input delay: 1 ms @ 60 Hz
- LED indicators for each channel (power, fault)
- Auto‑detection of module health via RIO scanner
Compatibility & Certifications
- Legacy PLC‑2, PLC‑3, PLC‑5 and SLC‑500 (1747‑SN)
- RIO protocol over Belden 9463 (or equivalent)
- UL listed, CSA certified, CE marked
- RoHS compliant
- Class I, Div 2 (hazardous locations)
Package Contents
- 1791‑8AC module (1 unit)
- Mounting hardware kit
- Quick start guide (printed)
- RIO connector plug (included)
Warranty & Shipping
12‑month warranty against defects. FedEx, UPS, DHL global express shipping available. All shipments insured and tracked.
Typical Applications
- Distributed I/O for conveyor systems
- Packaging machines with AC sensors/actuators
- Material handling and sortation
- Legacy plant retrofits (RIO networks)
- Remote monitoring of AC loads
Frequently Asked Questions
Q: Does this module work with ControlLogix?
A: Not directly. It requires a RIO scanner like 1756‑DNB or 1747‑SN.
Q: Can I mix input/output groups?
A: The module has 1 group of 8 inputs and 1 group of 8 outputs – fixed.
Q: What cable type is required?
A: Belden 9463 or equivalent twin‑axial cable for RIO.
Q: Is the module hot‑swappable?
A: No, power down before installation.
Q: Surge protection included?
A: Yes, built‑in transient suppression per channel.
Why Buy From Oiltech Controls?
- Over 15 years in industrial automation spares
- Global logistics – fast, reliable delivery
- All units tested and verified prior to shipping
- Surplus & refurbished options with 12‑month warranty
- Expert support for obsolete control systems
- Technical verification before dispatch
Contact Information
Email: info@oiltechcontrols.com
WhatsApp: +86 158 8020 0923
Copyright © 2026 Oiltech Controls Limited. All rights reserved.
Original Source: https://www.oiltechcontrols.com/
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