Product Overview
The Spectrum Controls 1771sc-IMI16 is a 16-point isolated AC/DC input module designed for Allen-Bradley 1771 I/O chassis systems used with PLC-5 and other legacy controllers. Unlike conventional input modules that share a common return across all channels, the 1771sc-IMI16 provides individual isolation for each input, with 1500V input-to-input isolation that eliminates concerns about crossing phases and enables mixed signal sources within a single module . This channel-to-channel isolation architecture allows engineers to connect devices powered by different supplies, voltages, or phases without risking ground loops or equipment damage.
The 1771sc-IMI16 operates over a broad voltage range of 159 to 264V AC and 184 to 276V DC, supporting both sinking and sourcing configurations . This high-voltage capability allows direct monitoring of 220/240V circuits without interposing relays or step-down transformers, reducing installation cost and panel complexity. The module is specifically designed for use with limit switches, float switches, selector switches, push-buttons, and proximity switches, meeting IEC requirements for proximity switch compatibility .
As a direct functional replacement for the Allen-Bradley 1771-IMD module, the Spectrum Controls 1771sc-IMI16 offers the same operational behavior with the added benefit of channel-to-channel isolation for improved noise suppression . The module installs in a standard 1771 I/O chassis slot and connects via the 1771-WN 40-terminal field wiring arm, drawing 100 mA maximum from the backplane supply . For legacy PLC-5 installations requiring reliable high-voltage discrete input acquisition, the 1771sc-IMI16 provides a practical upgrade path that preserves existing programming while enhancing electrical robustness.
Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | 1771sc-IMI16 |
| Manufacturer | Spectrum Controls (for Allen-Bradley 1771 systems) |
| Product Type | Isolated AC/DC Discrete Input Module |
| Input Channels | 16 |
| Points per Common | 1 (fully isolated per channel) |
| Input-to-Input Isolation | 1500 V |
| Nominal Input Voltage | 220/240V AC @ 50/60 Hz; 250V DC |
| AC Operating Range | 159 to 264V AC |
| DC Operating Range | 184 to 276V DC |
| On-State Current (Min) | 6.30 mA @ 159V AC, 50 Hz; 1.30 mA @ 184V DC |
| Off-State Voltage (Max) | 70V AC; 50V DC |
| Input Signal Delay (Off→On) | 11 ± 6 ms (AC); 3 ± 2 ms (DC) |
| Input Signal Delay (On→Off) | 29 ± 8 ms (AC); 30 ± 7 ms (DC) |
| Backplane Current | 100 mA maximum |
| Power Dissipation | 11.5 W maximum |
| Wiring Arm | 1771-WN (40-terminal) |
| Module Location | 1771 I/O chassis, single slot |
| Compatible Chassis | 1771 Series B or later |
