Discrete I/O Control Solution – Allen-Bradley 1791-32A0 | 1791 Block I/O Series
Where This Product Is Used
The Allen-Bradley 1791-32A0 Block I/O Module is deployed in hardwired discrete control architectures where distributed I/O must operate reliably in industrial environments without a dedicated backplane. Typical installation sites include:
- Automotive assembly lines – end-of-line testing stations, conveyor interlocks, and fixture clamping control
- Food & beverage packaging – filling machine sequencing, cap-torque verification, and reject gate actuation
- Material handling & warehousing – pallet transfer systems, sorter divert gates, and accumulation conveyor control
- Water & wastewater treatment – pump station control, valve position feedback, and level switch monitoring
- Discrete manufacturing – press brake interlocks, robotic cell safety fencing, and part-present sensing
- Oil & gas surface facilities – wellhead valve control, separator level monitoring, and ESD panel integration
The 1791-32A0 is particularly valued in retrofit projects where existing 1791 Series wiring infrastructure is preserved, reducing re-engineering cost and downtime.
Technical Specifications
| Parameter | Specification |
|---|---|
| Catalog Number | 1791-32A0 |
| Series | Allen-Bradley 1791 Block I/O |
| I/O Configuration | 32 Discrete Inputs / 0 Outputs (32A0 = 32 AC Inputs) |
| Input Voltage | 120V AC |
| Input Current (per point) | Approx. 10 mA @ 120V AC |
| Communication Interface | Allen-Bradley 1771 I/O chassis compatible (Block I/O adapter required) |
| Housing | IP65-rated block housing, DIN-rail or panel mountable |
| Operating Temperature | 0°C to +60°C (32°F to 140°F) |
| Storage Temperature | -40°C to +85°C |
| Weight | Approx. 900 g |
| Agency Approvals | UL Listed, CSA Certified, CE Marked |
Why Engineers Specify This Model
- High-density discrete input capture – 32 AC input points in a single compact block eliminate the need for multiple I/O cards and reduce panel footprint.
- 120V AC native compatibility – directly interfaces with standard industrial field devices (proximity switches, limit switches, pushbuttons) without interposing relays or signal converters.
- Distributed architecture support – Block I/O modules mount close to field devices, cutting field wiring runs and reducing noise susceptibility.
- Proven 1791 Series reliability – a platform with decades of installed base in North American and global manufacturing, with extensive spare-parts availability.
- Simplified maintenance – LED status indicators per input point enable rapid fault isolation without a laptop or diagnostic tool.
- Backward compatibility – drop-in replacement for existing 1791 Series installations; no PLC program changes required when substituting equivalent modules.
Complete System Bill of Materials
For a fully operational distributed I/O node using the 1791-32A0, the following components are typically required:
- 1791-32A0 – Block I/O Input Module (this item)
- 1791-A2B / 1791-A4B – Block I/O Adapter (2-slot or 4-slot, connects block to PLC I/O chassis)
- 1771-ASB – Remote I/O Adapter (if using remote I/O link topology)
- 1770-SC – Remote I/O Cable (Belden 9463 or equivalent shielded twisted-pair)
- 1771-P4S / 1771-P7 – Power Supply for 1771 chassis (if chassis-based architecture)
- Field wiring terminal blocks – Phoenix Contact or equivalent, rated for 120V AC
- 24V DC or 120V AC power supply – for field device power (sensor supply)
- DIN rail & enclosure – IP54 or higher rated panel for field-mount installations
Compliance & Industry Standards
- UL 508 – Industrial Control Equipment (UL Listed)
- CSA C22.2 No. 142 – Process Control Equipment (CSA Certified)
- CE Marking – EMC Directive 2014/30/EU; Low Voltage Directive 2014/35/EU
- RoHS Compliant – Restriction of Hazardous Substances (EU Directive 2011/65/EU)
- NEMA / IEC – Enclosure rated to IP65 per IEC 60529
- IEC 61131-2 – Programmable Controllers: Equipment Requirements and Tests (input signal compatibility)
Quality Assurance & Sourcing
Konmask.com sources Allen-Bradley 1791-32A0 modules through established industrial distribution channels with full traceability. Our quality process includes:
- Visual inspection – housing integrity, label legibility, connector condition, and date-code verification
- Functional verification – input channel continuity and LED indicator check prior to dispatch
- Authentic packaging – original Allen-Bradley / Rockwell Automation packaging retained where available; anti-static bagging applied for all shipments
- Documentation – Certificate of Conformance (CoC) available on request; original Rockwell Automation datasheets provided
- Warranty – 12-month warranty against manufacturing defects; advance replacement available for qualified accounts
How to Source This Part
- Add to cart on this page and proceed to checkout — standard lead time is 3–7 business days for in-stock units.
- Request a quote for volume orders (>5 units) or urgent requirements by emailing support@konmask.com.
- Provide your PO number for B2B net-term orders — we support NET 30 for approved accounts.
- Expedited shipping available via DHL Express, FedEx International Priority, or SF Express for time-critical plant shutdowns.
- Cross-reference check — if you are unsure whether the 1791-32A0 is the correct replacement for your application, contact our engineering team with your existing module catalog number and we will confirm compatibility.
Application-Specific FAQ
Q: Can the 1791-32A0 be used with a ControlLogix or CompactLogix PLC?
A: The 1791 Block I/O series was designed for use with PLC-5 and SLC 500 systems via the 1771 I/O chassis or Remote I/O link. Direct integration with ControlLogix/CompactLogix requires a 1747-ASB or FLEX I/O adapter bridge. Contact us for migration guidance.
Q: What is the maximum cable length for the Remote I/O link?
A: The Allen-Bradley Remote I/O link supports up to 3,048 m (10,000 ft) at 57.6 Kbps using Belden 9463 shielded cable. Shorter distances allow higher baud rates (115.2 Kbps or 230.4 Kbps).
Q: Is the 1791-32A0 still in production?
A: Rockwell Automation has discontinued active production of the 1791 Series. However, Konmask.com maintains stock of genuine surplus and refurbished units to support legacy system maintenance. Lead times may vary — contact us for current availability.
Q: Can I mix 1791-32A0 input modules with output modules on the same adapter?
A: Yes. The 1791 Block I/O adapter supports mixed input and output modules within the same I/O group, subject to the adapter’s total I/O point capacity. Refer to Allen-Bradley publication 1791-6.5.1 for configuration rules.
Q: What field devices are compatible with the 120V AC inputs?
A: Standard 120V AC field devices including NEMA-rated limit switches, inductive proximity sensors with AC output, pushbutton stations, float switches, and pressure switches are all directly compatible without signal conditioning.
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