Overview
The Allen-Bradley 1771-IVN is a Series C digital DC input module designed for use with PLC-5 programmable logic controllers and the 1771 I/O chassis family. This low true input module operates within a voltage range of 10 to 30 VDC. The module converts DC signals provided by user devices to the logic level needed by the processor, serving as the interface between field devices (switches, sensors, push buttons) and PLC processors.
Key Features
- 32 Digital Inputs: 32 inputs arranged in 4 sets of 8 with individual front-panel LED indicators for status monitoring
- Low-True Logic: Source input design requiring a sink output, providing enhanced noise immunity in industrial environments
- Noise Filtering & Protection: Input filtering reduces electrical noise, with optoelectrical isolation protecting circuits from electrical transients
- Status Indicators: 32 status indicators on the module front plate for real-time input monitoring and troubleshooting
- Compact Rack-Mount Design: Installs in 1771 I/O chassis containing a PLC processor with quick-change 1771-WN wiring arm compatibility
- Series C Revision: Includes latest firmware updates and improvements over earlier revisions
Technical Specifications
Input Characteristics:
- Input Voltage Range: 10–30V DC
- Nominal Input Current: 4.5 milliamperes
- Maximum Off-State Current: 1.7mA
- Input Impedance: 2.2 kilo ohms
- Signal Delay: 6ms (±2) in On-DC and Off-DC states
- Input Isolation Voltage: 500V tested for 60 seconds
Power & Performance:
- Backplane Current Draw: 280mA
- Power Dissipation: 15.6W maximum, 1.5W minimum
- Thermal Dissipation: 53.3 BTU/hr maximum
- Operating Temperature: 0 to 60°C (32 to 140°F)
- Storage Temperature: -40 to 85°C (-40 to 185°F)
- Relative Humidity: 5 to 95% (non-condensing)
Installation & Addressing:
- Module Slots: Supports ½ and 1-slot I/O addressing
- Data Table Usage: 32 input image bits in the data table
- Keying Pins: Pins 14–16 (lower connector) and pins 30–32 (upper connector)
- Wire Size: Category 1 conductors, 14 gauge (2 mm²) stranded
Certifications: CE marked, certified to CSA standards, and UL listed
Typical Applications
- Manufacturing automation and process control
- Food and beverage, oil and gas, and automotive industries
- Legacy PLC-5 system integration and upgrades
- Discrete input signal acquisition from switches, sensors, and push buttons
- Industrial equipment retrofit and replacement projects
- Control systems requiring noise-immune low-true input logic
Compatibility & Replacements
Compatible With
- PLC Controllers: All current chassis from the Allen-Bradley Bulletin 1771 product line
- I/O Chassis: 1771-A1B, 1771-A2B, 1771-A3B, 1771-A4B
- Wiring Arms: 1771-WN, 1771-WH (quick-change, no rewiring required)
- Power Supply: 1771 chassis backplane power supply
- Field Devices: DC sensors, switches, push buttons, proximity sensors requiring 10–30VDC
Replaces / Drop-In Replacement For
- Earlier 1771-IVN Series A and Series B revisions
- Limited compatibility as a direct replacement for other 1771 input modules—verify with system integrator for non-1771 systems
- Verify compatibility with your system integrator before ordering for legacy PLC systems
Works With
- Software Platforms: PLC-5 ladder logic programming via Allen-Bradley programming software
- Communication Protocols: Native 1771 backplane connection (not Ethernet or PROFINET)
- Configuration: Fault mode selection via configuration plug (last state or reset mode)
- Ecosystem: Rockwell Automation / Allen-Bradley industrial control systems using discrete DC input modules
