Allen Bradley1771IADAC/DC Input Module, 16 Point, 120 V AC/DC, 1771 I/O Chassis, Series B

Product Description

What this part is

Allen-Bradley 1771-IAD discrete input module, Series B. Product Type: high-density AC/DC digital input module for the 1771 I/O platform. Points: 16. Input Voltage: 120 V AC/DC. Operating Voltage Range: 79 to 138 V AC, 79 to 138 V DC. Backplane Current: 195 mA at 5 V DC. Mounting Type: 1771 I/O chassis slot. Unit Quantity: 1 Pc.

Decoding the designation

1771 — the Allen-Bradley 1771 I/O platform, the rack-based I/O family served by PLC-2, PLC-3 and PLC-5 processors.

IA — the 120 V AC/DC input group within that platform.

D — the double-density execution, giving 16 points in one slot where the plain 1771-IA gives 8.

Series B — the second hardware revision of the module.

Electrical data

Input Voltage: 120 V AC/DC. Operating Voltage Range: 79 to 138 V AC, 79 to 138 V DC. Points: 16. Backplane Current: 195 mA at 5 V DC. Power Dissipation: 8.8 W maximum, 1.0 W minimum. Thermal Dissipation: 30.1 BTU/hr maximum, 3.42 BTU/hr minimum.

Signal Delay: 5 ms ±3 ms on-state AC; 3 ms ±0.1 ms or 10 ms ±1 ms on-state DC; 25 ms ±5 ms off-state AC and DC.

What these specs mean in practice

Points: 16. Double density doubles the field devices a chassis slot carries, which is the whole reason to fit an IAD over an IA where rack space is the constraint.

Operating Voltage Range: 79 to 138 V AC. The band runs wider at the low end than the 8-point module’s, so a long control run with voltage drop still reads as a true input.

Backplane Current: 195 mA at 5 V DC. That is the figure that goes into the chassis power budget when a 1771-P series supply is sized against a full rack.

Signal Delay: 25 ms off-state against 5 ms on-state AC. The asymmetric filtering holds a bit true through the AC zero crossing and drops it cleanly when the field device really opens.

Power Dissipation: 8.8 W maximum. Combined with the 30.1 BTU/hr thermal figure, it sizes enclosure ventilation for a densely populated chassis.

Chassis compatibility

Chassis: 1771-A1B, 1771-A2B, 1771-A3B, 1771-A3B1, 1771-A4B, 1771-AM1 and 1771-AM2. Mounting Type: single slot. Terminations: removable field wiring arm. Signal Type: discrete on/off.

Quantity and configuration

Unit Quantity: 1 Pc. One input module.

Interchange guidance

Manufacturer Status: discontinued. Part Number: 1771-IAD. MPN Variants: 1771IAD, 1771 IAD. The 1771-IA is the 8-point module on the same voltage and the 1771-IAN the 32-point, so those change the point count and the chassis power budget. The 1771-ID16 is the 16-point isolated execution on the same voltage, where each point carries its own return. Series B and Series C of the 1771-IAD share the 16-point 120 V AC/DC configuration and the same 1771 chassis slot.