Overview
The Allen-Bradley 1771-IAD is a discrete input module designed for integration with PLC-5 control systems. This 16-point digital input module processes AC and DC signals in industrial automation applications, providing reliable interface between field devices and programmable logic controllers. The 1771-IAD/D is a Series D variant offering enhanced performance and compatibility with modern 1771 I/O chassis.
Key Features
- 16 Input Channels: Sixteen (16) input channels compatible for 120VAC / 125VDC input voltage
- AC/DC Signal Support: Accepts AC and DC signal voltages such as 120VAC with frequency of 50/60 Hz and 125VDC
- Opto-Isolation Protection: Contains optoelectrical isolation to protect the system circuits from electrical transients
- Input Filtering: Contains input filtering feature to reduce electrical noise
- Field-Wiring Arm: Uses a field wiring arm of 1771-WH comparable to removable terminal blocks, which is used for modular wiring and simplified installation and maintenance
- Status Indicators: Has 1 green module active indicator and 16 red status indicators for system logic side indication at the front panel
Technical Specifications
- Input Signal Delay (AC): 120V ac/60Hz: 5ms (+3ms) or 20ms(+5ms) selectable
- Input Signal Delay (DC): 120V dc: 3ms (+0.1ms) or 10ms (+1ms) selectable for Off to On transition
- Off-to-On Delay (AC/DC): 25ms (+5ms) for 120V ac or dc for ON to OFF transition
- Off-State Leakage Current: Maximum Off-state current of 3mA for AC and 0.8mA for DC
- Backplane Current: 195mA backplane current load
- Power Dissipation: Maximum power dissipation of 8.8W and thermal dissipation of 30.1 BTU/hr
- Slot Support: Supports ½, 1, and 2-slot I/O addressing
- Series: D
- Weight: 0.99 lbs
Typical Applications
The 1771-IAD is primarily used to interface discrete devices such as pushbuttons, switches of different varieties, auxiliary contacts from relays, contactors and other devices. Common applications include:
- Machine control and automation systems
- Industrial process monitoring
- Equipment status and alarm input capture
- Sensor and switch signal conditioning
- Motor starter and contactor feedback
Compatibility & Replacements
Compatible for installation in 1771-A1B, A2B, A3B, A3B1, A4B, 1771-AM1 and AM2 chassis. The 1771-IAD is part of the 1771 product family designed for PLC-5 controllers. As of March 10, 2020, the 1771 16 Point Digital Input Module has been discontinued and no longer available for sale, making surplus units valuable for system maintenance and replacement needs. Verify current module series variant (B, C, or D) before ordering to ensure compatibility with your specific 1771 I/O chassis configuration.
