The Allen Bradley 1771-IFM is a PLC-5 series fast millivolt analog input module designed for the 1771 I/O chassis platform. It is engineered to accurately measure very low-level millivolt signals from industrial sensors and transducers, making it suitable for high-sensitivity process monitoring applications.
This module is typically used in systems requiring precise measurement of differential low-voltage signals such as strain gauges, thermocouples (via conditioning), and specialized instrumentation.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Allen Bradley (Rockwell Automation) |
| Catalog Number | 1771-IFM |
| Module Type | Fast Millivolt Analog Input Module |
| System Family | PLC-5 / 1771 I/O |
| Input Channels | 8 differential inputs |
| Input Signal Range | 0–50 mV (low-level millivolt signals) |
| Resolution | 12-bit binary |
| Accuracy | ±0.1% of full scale @ 25°C |
| Linearity | ±1 LSB |
| Repeatability | ±1 LSB |
| Input Protection | Up to 32 V overvoltage protection |
| Max Input Voltage | ±10 V DC (protection limit) |
| Update Time | ~14–15 ms per 8 channels |
| Backplane Current Draw | ~750 mA @ 5 V DC |
| Data Format | Binary / BCD selectable |
| Isolation | Channel-to-channel and system isolation |
| Wiring Arm | 1771-WF (typical for IFM series) |
| Mounting Type | 1771 chassis slot (1-slot width) |
| Operating Temperature | 0°C to 60°C |
| Storage Temperature | -40°C to 85°C |
| Weight | ~0.5–0.6 kg |
| Dimensions (L×W×H) | 203 mm × 76 mm × 127 mm |
System Role Overview
The 1771-IFM module is designed for high-sensitivity analog measurement, specifically targeting low-level millivolt signals that require fast and accurate conversion.
Core functions include:
- Acquisition of low-level millivolt sensor signals
- High-speed analog-to-digital conversion
- Differential signal measurement for noise rejection
- Industrial-grade signal conditioning interface
- Integration with PLC-5 block transfer instructions
It is often used where standard 0–10V or 4–20mA modules cannot provide sufficient sensitivity.
Recommended Related Modules
| Model | Function |
|---|---|
| 1771-IFE | Standard analog input module |
| 1771-IFF | High-resolution analog input module |
| 1771-IBD | DC digital input module |
| 1771-IBN | High-density DC input module |
| 1771-OBD | Digital output module |
| 1771-ASB | Remote I/O adapter |
Common PLC-5 System Modules
| Model | Role |
|---|---|
| 1785-L40B | PLC-5 processor |
| 1771-A4B | 16-slot I/O chassis |
| 1771-DMC | Data Highway communication module |
| 1771-SN | I/O scanner module |
| 1771-ALX | Local I/O adapter module |
