Allen-Bradley 1746-NI16I/A Analog Input Module

The Allen-Bradley 1746-NI16I/A, also cataloged as the 1746-NI16I/A analog input module, serves as the primary 1746-NI16I/A current input module utilized to execute 0–20 mA and 4–20 mA signal acquisition across SLC 500 backplane scan-based I/O architectures. The module digitizes 16-channel current loop signals using sigma-delta conversion with programmable filtering into 16-bit resolution process data.

Suffix Breakdown & Model Matrix

No suffix segmentation is defined for 1746-NI16I/A. The designation represents a fixed 16-channel current input configuration within the SLC 500 NI16 analog input family.

Hardware Specifications

SLC 500 Backplane Current Signal Acquisition Architecture

The 1746-NI16I/A performs multiplexed current loop sampling across 16 input channels using sigma-delta conversion stages with programmable digital filtering. Each channel is time-sliced into the internal acquisition pipeline, where filtering parameters define the effective bandwidth between 6 Hz and 250 Hz, directly influencing step response behavior.

Converted values are transferred into SLC 500 input image tables via deterministic backplane scan cycles. The module maintains separation between acquisition and processing domains, allowing stable representation of low-level current signals under variable electrical noise conditions. Channel grouping is internally segmented into 4-channel blocks with shared status indicators for diagnostic visibility.

Frequently Asked Questions (FAQ)

Q: Can the 1746-NI16I/A be hot-swapped in a powered SLC 500 rack?
A: No. Module insertion and removal require chassis power shutdown due to backplane electrical coupling design.

Q: How does filtering affect module response time?
A: Step response varies between 9 ms and 630 ms depending on selected digital low-pass filter bandwidth (6–250 Hz), directly affecting signal update latency.

Q: What is the backplane power load of this module?
A: The module consumes 125 mA at 5 V DC and 75 mA at 24 V DC, which must be included in SLC 500 rack power calculations.

Field Installation Guidelines

Install the module in a compatible SLC 500 chassis slot with verified backplane capacity. Use shielded twisted-pair cable such as Belden 8761 for all current loop inputs. Maintain separation between analog signal wiring and high-voltage conductors to minimize electromagnetic coupling. Terminate cable shields at a single-point ground on the panel side only. Ensure terminal block seating integrity before energizing the system. Verify loop compliance within specified current ranges (0–20 mA, 4–20 mA, ±20 mA) to prevent saturation of the sigma-delta conversion stage.