Overview
The Allen-Bradley 1791-32B0 Block I/O module is a compact, self-contained input device engineered for distributed I/O control in industrial automation systems. This 32-input module features integral power conditioning, isolated input groups, and RIO protocol communication, making it ideal for remote sensor acquisition in manufacturing, process control, and material-handling applications where PLC-2/3/5 family controllers are deployed.
Key Features
- 32 digital input channels logically arranged in four isolated groups of eight inputs each
- 24V DC nominal operation (10–30V DC input range)
- 300mA external power supply current draw—complies with cabinet power budgeting
- 500 Volts AC isolation between power, RIO, and I/O groups for robust noise immunity
- Universal Remote I/O (RIO) communication protocol for legacy PLC systems
- Removable terminal strips for fast installation and maintenance without rewiring
- Internal protection—no external fuses required for input circuits
- Series B design certified for 0–60°C ambient operation
Technical Specifications
- Input Channels: 32 DC (four isolated groups of 8)
- Supply Voltage: 19.2–30V DC external; 10–30V DC on-state range
- Supply Current: 300 mA
- On-State Current (nominal): 11 mA @ 30V DC maximum
- Off-State Voltage: 5V DC maximum
- Off-State Current (minimum): 1.5 mA
- Input Impedance (maximum): 3.4 kΩ
- Power Dissipation: 16.3 Watts maximum (55.6 BTU/hr)
- Isolation: 500V AC (power-to-RIO, I/O group-to-group, I/O group-to-logic)
- Mounting: Vertical or horizontal (with ventilation)
- Dimensions: 6.95 × 4.35 × 3.85 inches
- Operating Temperature: 0–60°C ambient
- Wire Specification: 2.0 mm² (14 AWG) solid standard wire; maximum insulation 3/64 inch
- Series: 1791 Block I/O
Typical Applications
- Manufacturing Automation: Assembly lines, packaging systems, and material-handling equipment requiring distributed discrete I/O
- Process Control: Remote monitoring and control of pumps, valves, solenoids, and limit switches
- Machine Control: Real-time sensor data acquisition for proximity switches, photoelectric sensors, and push buttons
- Remote I/O Distribution: Extending PLC I/O capacity to satellite locations via RIO network without long cable runs
Compatibility & Replacements
Compatible With
- Allen-Bradley PLC-2 family controllers
- Allen-Bradley PLC-3 family controllers
- Allen-Bradley PLC-5 series controllers (including PLC-5/250)
- Allen-Bradley SLC 5/02 modular controllers
- 1771-series output modules (verify off-state leakage current <1.5 mA)
- Universal Remote I/O (RIO) networks
Replaces / Drop-In Replacement For
- 1791-32A0 (Series A 32-input module—Series B is enhanced version)
- Equivalent 1791 Block I/O configurations from earlier production runs
Works With
- Universal Remote I/O (RIO) protocol for PLC-2, PLC-3, PLC-5, and SLC 500 systems
- Allen-Bradley control platforms via DH-485 communication backbone
- Legacy PLC programming software: RSLogix 500 (for SLC 500 indirect compatibility), PLC-5 native editors
