Product Introduction
The Allen-Bradley 1771-IM is a Digital AC/DC Input Module designed for the PLC-5 family of programmable controllers. This industrial automation module provides eight inputs to monitor selector switches, pushbutton switches, AC limit switches, and float switches. It accepts both AC and DC signals, making it a flexible choice for mixed-voltage control panels.
With a voltage category of 220 Volts AC/DC, the 1771-IM supports an operating range of 184-276 Volts for both AC and DC inputs. This wide tolerance ensures stable operation even in facilities with fluctuating line voltages.
Technical Specifications
The following specifications are taken directly from the manufacturer's data for the Allen-Bradley 1771-IM:
| Parameter |
Value |
| Manufacturer |
Rockwell Automation |
| Brand |
Allen-Bradley |
| Part Number / Catalog No. |
1771-IM |
| Module Type |
Digital AC/DC Input Module |
| Number of Inputs |
8 Inputs |
| Voltage Category |
220 Volts AC/DC |
| AC Operating Voltage |
184-276 Volts |
| DC Operating Voltage |
184-276 Volts |
| Backplane Current |
75 Milliamperes |
| Max AC Off-State Current |
1.0 Milliamperes |
| Max DC Off-State Current |
1.0 Milliamperes |
| Typical AC Signal Delay (On) |
20 (+/- 6) ms |
| Typical DC Signal Delay (On) |
10 (+/- 4) ms |
| Typical AC Signal Delay (Off) |
20 (+/- 6) ms |
| Typical DC Signal Delay (Off) |
20 (+/- 9) ms |
| Wiring Arm |
1771-WA |
| Mounting |
Rack Mountable |
Additional electrical characteristics include a minimum on-state current of 2.9 mA, a maximum off-state current of 1 mA, and a maximum off-state voltage of 92-114V AC. Power dissipation ranges from 0.4 W to 2.4 W, with thermal dissipation from 3.2 BTU/hr to 10.9 BTU/hr. The module operates within a non-condensing relative humidity of 5-95% and an operating temperature of 32-140°F (0-60°C).
Industry Applications
The 1771-IM is ideal for applications that require reliable monitoring of discrete field devices. Common use cases include:
-
Machine control: Monitoring limit switches and pushbuttons on production equipment.
-
Process control: Reading float switch states in tanks or hoppers.
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Material handling: Detecting the position of actuators or conveyor sensors.
Its ability to handle both AC and DC signals simplifies wiring and reduces the need for separate input modules, which can lower overall system cost and inventory requirements.
Installation & Setup
Mount the 1771-IM in any available slot of a PLC-5 rack. Ensure the backplane connector is fully seated and secure the module with the provided screws. Use the 1771-WA wiring arm for field wiring; terminate each input according to the module's wiring diagram. Verify that the input voltage is within the 184-276V range before powering the system. For DC inputs, observe polarity as indicated on the wiring arm.
Maintenance & Reliability
Periodically inspect the module for dust accumulation and ensure the rack's cooling fans are operational. Check the wiring arm connections for tightness, especially in high-vibration environments. The module's wide operating temperature range and non-condensing humidity tolerance make it suitable for demanding industrial settings. Routine checks of input signal timing can help detect potential issues early.
Compatibility & Integration
The 1771-IM is designed for the Allen-Bradley PLC-5 family. It communicates with the PLC processor via the backplane, requiring no additional communication modules. The module is compatible with 1771 series racks and can be integrated into existing PLC-5 systems without modification.
Selection Guide & Purchasing Advice
Before purchasing, verify that the 1771-IM is the correct input module for your application by checking the voltage category and number of inputs. Confirm that your PLC-5 rack has an available slot and that the backplane current draw (75 mA) is within the power supply's capacity. For a reliable source, consider PLC Source PRO, a trusted supplier of industrial automation parts.