Product Description

The Allen-Bradley 1756-IM16I stands as a high-performance ControlLogix Isolated Digital Input Module specifically for demanding AC voltage sensing applications. This module fits directly into the I/O Modules product category and delivers 16 individually isolated inputs. Each channel operates independently, so ground loop issues disappear and signal integrity improves significantly in noisy industrial environments. Furthermore, the 1756-IM16I supports a wide operating voltage range of 159 to 265 Volts AC, which makes it exceptionally versatile for global automation systems running at 240V AC, 50/60 Hz.

Technical Specifications

The 1756-IM16I excels under extreme conditions thanks to its robust engineering. The nominal input voltage sits at 240 Volts AC, while the on-state current varies from 5 mA at 159V AC to 13 mA at 265V AC. Meanwhile, the off-state maximum input current remains low at 2.5 mA to minimize leakage current. For precise timing control, the module offers programmable input delay times: the hardware delay reaches 10 ms max (off-to-on) and 8 ms max (on-to-off), and users can select additional filter times (1/2 ms for off-to-on; 9/18 ms for on-to-off). Consequently, the module draws 100 mA at 5V and 3 mA at 24V from the backplane, with total backplane power consumption of only 0.58 Watts. Moreover, maximum power dissipation peaks at 5.8 Watts at 60°C, translating to a thermal dissipation of 19.78 BTU/hour.

Environmental Tolerance & Immunity

This module thrives in harsh industrial settings. For instance, it operates reliably across a wide temperature range, though users should note derating curves: full operation at 60°C with all channels ON requires voltage derating to 159-242V AC. Additionally, the isolated inputs provide exceptional noise immunity, so the 1756-IM16I delivers stable readings even amid strong electromagnetic interference (EMI) and transient surges. Likewise, the module supports a maximum inrush current of 250 mA, which effectively protects the circuit during power-up.

Installation Guidelines

Before installing the 1756-IM16I, always power down the system completely. Next, insert the module into any available slot within a ControlLogix chassis (compatible models include 1756-A4, 1756-A7, 1756-A10, 1756-A13, or 1756-A17) until it clicks securely into place. Then, choose a compatible 36-pin Removable Terminal Block (RTB) for field wiring—specifically, select either the 1756-TBCH (screw-clamp type) or the 1756-TBS6H (spring-clamp type). After that, connect the AC power leads to the designated terminals on the RTB, ensuring proper isolation per point. Once wiring completes, insert the RTB into the front of the 1756-IM16I and tighten the retaining screws firmly. Finally, reapply power and configure the input filter times and change-of-state settings through the Rockwell Automation programming software.

Package Contents

• 1 x Allen-Bradley 1756-IM16I ControlLogix Isolated Input Module

• 1 x Removable Terminal Block (RTB) – 1756-TBCH or 1756-TBS6H (depending on stock/region)

• 1 x Installation Instructions booklet (pub. 1756-IN005)

• 1 x Module identification label

Note: Chassis, power supply, and communication cables require separate purchase.

Frequently Asked Questions (FAQ)

Q1: What differentiates the 1756-IM16I from the standard 1756-IM16?
A: The 1756-IM16I features individually isolated inputs (per-point isolation), whereas the standard 1756-IM16 uses group isolation. Therefore, the 1756-IM16I delivers superior noise rejection and better protection against ground potential differences, which makes it ideal for distributed I/O applications.

Q2: Which RTB (Removable Terminal Block) works with the 1756-IM16I?
A: The 1756-IM16I accepts 36-pin RTBs: the 1756-TBCH (screw-clamp) and the 1756-TBS6H (spring-clamp). For proper fit and electrical safety, always use one of these specific models.

Q3: Can users adjust the input filter time on the 1756-IM16I?
A: Yes. For the 1756-IM16I, users can select the off-to-on filter at 1 ms or 2 ms, and the on-to-off filter at 9 ms or 18 ms. Configuration takes place via the I/O configuration tree in your Rockwell Automation software to match your application's response speed requirements.

Q4: What maximum temperature does the 1756-IM16I support with all 16 points active?
A: With all 16 channels ON, the 1756-IM16I operates at up to 60°C, but the AC voltage range must derate to 159-242V AC (at 47-63 Hz). At 30°C, the full 159-265V AC range remains available with all channels ON.

Q5: Does the 1756-IM16I fit into other brands' PLC racks?
A: No. The 1756-IM16I works exclusively within the Allen-Bradley ControlLogix 1756 chassis platform. It is neither mechanically nor electrically compatible with other manufacturers' systems.