Allen Bradley1771-IAAC/DC Input Module, 8 Point, 120 V AC/DC, 1771 I/O Chassis, Series B

Product Description

What this part is

Allen-Bradley 1771-IA discrete input module, Series B. Product Type: AC/DC digital input module. Points: 8. Input Voltage: 120 V AC/DC. Groups: 1. Points per Group: 8. Backplane Current: 75 mA. 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 8-point 120 V AC/DC input module within that platform.

Series B — the second hardware revision of the module.

Electrical data

Input Voltage: 120 V AC/DC. On-State Voltage Range: 87 to 138 V AC, 97 to 138 V DC. Nominal Input Current: 7.9 mA per point at 120 V AC 60 Hz, 6.83 mA per point at 120 V AC 50 Hz, 7.4 mA per point at 125 V DC. Backplane Current: 75 mA. Power Dissipation: 10.7 W maximum. Thermal Dissipation: 36.5 BTU/hr maximum.

What these specs mean in practice

Points: 8, in one group sharing a single common. Eight field devices land on one module, which is the density that suits a machine panel wired from one 120 V control circuit.

On-State Voltage Range: 87 to 138 V AC. That band covers a nominal 120 V control circuit across normal supply variation, so a sagging line still reads as a true input.

Backplane Current: 75 mA. This is the figure that goes into the chassis power budget when a 1771-P series supply is sized against a full rack.

Power Dissipation: 10.7 W maximum. Combined with the 36.5 BTU/hr thermal figure, it sizes enclosure ventilation for a densely populated chassis.

Input Voltage: 120 V AC/DC. The module accepts either, so the same catalogue number covers AC control circuits and 125 V DC control circuits.

Mounting data

Mounting Type: single slot in a 1771 I/O chassis. Terminations: removable field wiring arm. Signal Type: discrete on/off. Operating Temperature: 0 to 60 °C. Storage Temperature: −40 to 85 °C.

Quantity and configuration

Unit Quantity: 1 Pc. One input module.

Interchange guidance

Manufacturer Status: discontinued. Part Number: 1771-IA. MPN Variants: 1771IA, 1771 IA. Within the same 120 V AC family the 1771-IAD is the 16-point module and the 1771-IAN the 32-point, so those change the point count and the chassis power budget. The 1771-IA2 is the isolated-group execution on the same voltage. Series A, B and C of the 1771-IA share the 8-point 120 V AC/DC configuration and the same 1771 chassis slot.