Product Overview
The Allen-Bradley 1771-IAD is a discrete input module designed for the 1771 family of Programmable Logic Controllers (PLCs). It accepts both AC and DC signal voltages, including 120VAC at 50/60 Hz and 125VDC. With sixteen (16) input channels, it interfaces seamlessly with discrete devices such as pushbuttons, switches, relay contacts, and contactors.
Part of the 1771 product bulletin, the 1771-IAD is compatible with a variety of 1771 chassis, including 1771-A1B, A2B, A3B, A3B1, A4B, 1771-AM1, and AM2. Its modular design and field wiring arm simplify installation and maintenance, making it a practical choice for expanding input capacity in existing control systems.
Technical Specifications
| Parameter |
Value |
| Part Number |
1771-IAD |
| Module Type |
Digital AC/DC Input Module |
| Number of Inputs |
16 Inputs |
| Voltage Category |
120 Volts AC/DC |
| AC Operating Voltage |
79-138 Volts |
| DC Operating Voltage |
79-138 Volts |
| Typical AC Signal Delay (On) |
5 (+/- 3) ms |
| Typical DC Signal Delay (On) |
3 (+/- 0.1) or 10 (+/- 1) ms |
| Typical AC Signal Delay (Off) |
25 (+/- 5) ms |
| Typical DC Signal Delay (Off) |
25 (+/- 5) ms |
| Max AC Off-State Current |
2.8 Miliamperes |
| Backplane Current |
195 Miliamperes |
| Wiring Arm |
1771-WH |
| Dimensions |
3.5 x 6.5 x 2.0 in (89 x 165 x 51 mm) |
Key Features & Benefits
-
16 input channels for monitoring a wide range of discrete field devices.
-
Versatile voltage range of 79-138V AC/DC enables use in both AC and DC control circuits.
-
Selectable signal delays allow tuning response times to match application requirements.
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Field wiring arm (1771-WH) simplifies wiring replacement without disconnecting field wiring.
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Backplane current draw of 195 mA ensures reliable communication with the PLC processor.
Industry Applications
The 1771-IAD excels in industrial environments where reliable discrete input monitoring is critical. Typical applications include:
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Manufacturing lines: Monitor pushbuttons and limit switches to control machine sequencing and safety interlocks.
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Material handling: Interface with proximity sensors and conveyor status contacts for automated sorting and routing.
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Process control: Capture auxiliary contacts from relays and contactors to verify equipment status in chemical or food processing plants.
Installation & Setup
When installing the 1771-IAD, select a compatible 1771 chassis (A1B through A4B, AM1, AM2). The module requires keying bands set between pins 10 and 12 or 14 and 16 to ensure correct slot placement. Attach the 1771-WH wiring arm to connect field wiring; this removable terminal block simplifies replacement and maintenance. Always power down the chassis before insertion to avoid damage.
Maintenance & Reliability
The 1771-IAD is built for long service life with optoelectrical isolation that protects circuits from electrical transients. Its input filtering reduces electrical noise, enhancing reliability in industrial settings. Routine inspection of the wiring arm and status indicators—1 green active LED and 16 red channel LEDs—helps detect issues early. Periodic cleaning of the module and chassis vents prevents dust buildup that could affect heat dissipation.
Compatibility & Integration
This module is compatible with all 1771 I/O chassis and works with PLC-5 processors. It supports ½, 1, and 2-slot I/O addressing, offering flexibility in system configuration. The 1771-IAD is a Series D module, ensuring broad compatibility within the 1771 family.
Selection Guide & Purchasing Advice
Before purchasing the Allen-Bradley 1771-IAD, verify your chassis model and required input voltage (120V AC/DC). Confirm the number of inputs needed and whether the 1771-WH wiring arm is included or must be ordered separately. PLC Source PRO offers genuine 1771-IAD modules with fast shipping and competitive pricing, backed by industry expertise.