Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | 1756‑IH16I/A |
| Manufacturer | Allen‑Bradley (Rockwell Automation) |
| Product Type | ControlLogix Digital Input Module |
| Number of Channels | 16 individually isolated inputs |
| Input Voltage Range | 90 to 146 VDC (Nominal 125 VDC) |
| Input Type | Sink/Source, 2‑wire |
| On‑State Current | 1 mA min @ 90 VDC, 3 mA max @ 146 VDC |
| Off‑State Voltage | ≤ 20 VDC |
| Input Delay (Off→On) | 2 ms max (hardware) + selectable filter time |
| Input Delay (On→Off) | 6 ms max (hardware) + selectable filter time |
| Filter Times (Selectable) | 0 ms, 1 ms, 2 ms, 9 ms, 18 ms |
| Backplane Current | 125 mA @ 5.1 VDC, 3 mA @ 24 VDC |
| Power Dissipation | 5 W max @ 60 °C |
| Isolation Voltage | 250 V continuous (input‑to‑input, input‑to‑backplane) |
| Operating Temperature | 0 to 60 °C (32 to 140 °F) |
| Terminal Block | Requires 1756‑TBCH or 1756‑TBS6H (sold separately) |
Main Features and Advantages
Individual Channel Isolation: Unlike grouped or common‑bus modules, the 1756‑IH16I/A provides full electrical isolation between each of its 16 input channels and the backplane. This design prevents noise and voltage transients on one channel from affecting adjacent channels or the central controller, significantly enhancing system reliability in electrically noisy environments such as plants with heavy motor drives or welding equipment.Configurable Filtering for Signal Integrity: The module offers software‑selectable filter times ranging from 0 ms to 18 ms. This allows engineers to tailor the response time to the specific field device, effectively debouncing mechanical contacts or filtering out electromagnetic interference without requiring external hardware. This flexibility ensures accurate state detection while minimizing the risk of false trips due to signal noise.High‑Voltage DC Compatibility: Designed for industrial control voltages, the 1756‑IH16I/A operates reliably with standard 125 VDC control circuits commonly found in motor starters, breaker status monitoring, and legacy control panels. Its wide operating range (90–146 VDC) accommodates voltage fluctuations and ensures stable operation even under sub‑optimal power conditions.Seamless ControlLogix Integration: As a native 1756 series module, it integrates directly into the ControlLogix backplane, supporting electronic keying for configuration control and utilizing the system’s high‑speed deterministic data exchange. Status LEDs for each channel provide immediate visual diagnostics, reducing troubleshooting time during commissioning and operation.
Application Field
The 1756‑IH16I/A is primarily deployed in industrial sectors requiring high‑voltage DC status monitoring and robust noise immunity. In manufacturing automation, it is used to read the status of limit switches, relay contacts, and selector switches on automotive assembly lines and material handling systems. Within the power generation and distribution sector, it monitors circuit breaker auxiliary contacts, disconnect switch positions, and protective relay outputs in switchgear and substation control systems. The module’s isolation capabilities make it suitable for harsh environments such as mining, where long cable runs are susceptible to induced voltages, and for water/wastewater treatment plants, where it interfaces with pump control circuits and high‑level alarms. Its ability to handle 125 VDC signals also makes it ideal for retrofitting older control panels into modern ControlLogix systems without the need for additional signal conditioning modules.
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