Overview
The Allen-Bradley 1771-OBD is a 16-channel, non-isolated discrete DC output module from the Allen-Bradley 1771 product line. Built for legacy PLC-5 systems and universal I/O chassis applications, this sourcing-type output module provides reliable control of low-voltage DC field devices including solenoids, contactors, pilot lamps, and relay coils. The 1771-OBD operates across a flexible voltage range of 10–60VDC with a nominal output of 48VDC, making it suitable for diverse industrial control requirements.
Key Features
- 16 individually controlled non-isolated output points
- Sourcing (positive logic) output configuration for direct device activation
- Output voltage range: 10–60VDC (nominal 48VDC)
- Per-channel current rating: 2A resistive, 0.2A pilot duty; module maximum 8A
- Surge current capacity: 4A per output (10ms, repeatable every 2s) or 25A per output (10ms, repeatable every 2s)
- Fast signal transition: 0.1ms off-to-on, 0.2ms on-to-off
- Mounts directly to 1771-A1B through 1771-A4B I/O chassis (excludes 1771-A4)
- Front-panel LED indicators for module status and individual output states
Technical Specifications
- Output Points: 16 non-isolated channels
- Output Voltage: 10–60VDC (nominal 48VDC)
- Current Rating per Channel: 2A resistive, max 8A per module
- On-State Voltage Drop: 1.5V DC
- Off-State Leakage Current: 0.5 mA maximum
- Minimum Load Current: 2.5 mA
- Response Time: <1 ms (off-to-on 0.1ms, on-to-off 0.2ms)
- Backplane Current: 400 mA @ 5V DC
- Power Dissipation: 15.6W maximum
- Thermal Dissipation: 53.3 BTU/hr
- Operating Temperature: 0°C to 60°C (32°F to 140°F)
- Storage Temperature: −40°C to 85°C (−40°F to 185°F)
- Humidity Range: 5–95% non-condensing
- Operating Shock: 30G (3-pulse, 11ms)
- ESD Immunity: 4 kV contact, 8 kV air discharge
Typical Applications
The 1771-OBD is commonly used in legacy PLC-5 automation systems for:
- Controlling DC solenoid valves and actuators
- Driving pilot indicator lamps and status lights
- Switching relay coils and contactors
- Operating alarm horns and warning devices
- Managing discrete on/off field I/O in manufacturing and process control
- Retrofit and replacement applications in established production lines
Compatibility & Replacements
Compatible With
- PLC-5 controllers and programming systems
- 1771-A1B, 1771-A2B, 1771-A3B, and 1771-A4B universal I/O chassis (not 1771-A4)
- Allen-Bradley legacy discrete I/O modules (1771-IQ, 1771-IBD, 1771-IBN, 1771-ICD, 1771-IB, 1771-IQ16, 1771-IC input modules)
- Field wiring arms: 1771-WH, 1771-WHF, 1771-WHFB
- Classic and legacy Allen-Bradley automation platforms
Replaces / Drop-In Replacement For
The 1771-OBD/C is the replacement revision for earlier 1771-OBD versions. Earlier output modules with similar functionality but different revisions can be directly replaced by this unit. Verify compatibility with your system integrator before ordering to ensure proper revision matching.
Works With
- Allen-Bradley PLC-5 ladder logic programming
- RSLogix 5 development software
- 1771 series I/O addressing and configuration
- Classic Allen-Bradley control architecture and networks
- Direct field wiring without isolation transformers or signal conditioning (sourcing outputs)
