Product Overview
The Allen-Bradley 1771-HS3A is a three-axis servo controller module from the PLC-5 product line, designed for installation in Bulletin 1771 I/O chassis. As a member of the IMC-120 series (also designated IMC-123 for the three-axis variant), the 1771-HS3A executes motion control functions by processing resolver or encoder feedback and generating ±10V DC analog command outputs for servo drives and amplifiers . The module occupies two slots per expansion chassis and requires the 1771-PS7 power supply for operation, connected via a 9-pin 1771-CAS cable .
The Allen-Bradley 1771-HS3A supports both resolver and encoder feedback configurations. When using resolver feedback, the module’s excitation circuit generates sine and cosine signals to energize the resolver stator, enabling precise position and velocity measurement in demanding industrial environments . For encoder feedback, the module accepts differential inputs up to 250 kHz and single-ended inputs at 20 kHz, with 10V DC isolated outputs for clean signal transmission . The module maintains a 2 ms per-axis update period, ensuring responsive closed-loop control for multi-axis coordination tasks .
Program storage and parameter retention are handled by the 1771-HMA 96 KB battery-backed memory cartridge, which holds AMP parameters and MML downloaded programs through power cycles . The 1771-HS3A provides an RS-232 port for connection to T45 or T50 Operating Data Stations (ODS), and supports optional hand-held pendants for on-the-floor parameter adjustment and system tuning . With c-UL, C-TICK, and CE certifications, the module meets international safety and electromagnetic compatibility standards for industrial automation equipment .
Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | 1771-HS3A |
| Manufacturer | Allen-Bradley / Rockwell Automation |
| Product Type | 3-Axis Servo Controller Module |
| Product Line | PLC-5 / IMC-120 Series (IMC-123) |
| Axes | 3 |
| Analog Output | ±10V DC command |
| Encoder Input (Differential) | 250 kHz maximum |
| Encoder Input (Single-Ended) | 20 kHz maximum |
| Module Update Period | 2 ms per axis |
| Backplane Current | 1.7 A |
| Fuse Voltage | 120 V |
| Memory Cartridge | 1771-HMA, 96 KB battery-backed |
| Required Power Supply | 1771-PS7 (120-240V AC, 1A/2A) |
| Communication | RS-232 (to T45/T50 ODS) |
| Wiring Arm | 1771-WA |
| Slots Occupied | 2 per expansion chassis |
| Operating Temperature | 0…60°C |
| Humidity | 5…95% non-condensing |
| Certifications | c-UL, C-TICK, CE |
