Allen-Bradley 1746-IH16 SLC 500 Digital DC Input Module

The Allen-Bradley 1746-IH16, also cataloged as the 1746-IH16 Digital DC Input Module, serves as the primary 16-point sinking input module utilized to execute 90–146 VDC discrete signal acquisition across SLC 500 backplane I/O architectures.

Configured for high-voltage DC input monitoring within SLC 500 chassis scan cycles, the module converts 16-channel sinking field signals into controller-readable logic states. Input conditioning supports defined off-state leakage thresholds and fixed scan-based update behavior via the backplane bus.

Suffix Breakdown & Model Matrix

No structured suffix segmentation is defined for 1746-IH16. The part number is a fixed SLC 500 catalog identifier without configurable hardware option extensions.

Hardware Specifications

Backplane Bus Communication and I/O Scan Execution

The module communicates input state transitions through the SLC 500 backplane during cyclic scan execution. All 16 channels are mapped as fixed discrete points without scaling or filtering layers. Backplane consumption remains constant at 85 mA @ 5 VDC regardless of switching activity. Signal updates are synchronized to controller scan timing with deterministic refresh behavior.

High-Voltage DC Sinking Input Conditioning

Input channels are configured for sinking operation across a 90–146 VDC range. Internal circuitry enforces off-state discrimination up to 0.8 mA leakage current and 20 VDC residual voltage tolerance. This prevents false triggering under induced or floating field conditions while maintaining stable logic transitions under high-voltage DC switching.

Frequently Asked Questions (FAQ)

Q: Does the 1746-IH16 support hot-swapping in an energized SLC 500 chassis?
A: No. Module installation or removal requires complete backplane power isolation to prevent bus corruption and transient fault conditions.

Q: What is the backplane load under full 16-channel operation?
A: Backplane consumption remains fixed at 85 mA @ 5 VDC independent of input state changes.

Q: Can the module tolerate residual voltage on OFF-state inputs?
A: Yes. OFF-state tolerance is defined up to 20 VDC with leakage current limit of 0.8 mA.

Field Installation Guidelines

Installation shall be performed in a compatible SLC 500 chassis slot with verified backplane alignment prior to energization. The module shall be fully seated and secured before field wiring is applied.

Field conductors must follow high-voltage DC separation rules, maintaining physical distance from low-level signal wiring. Shield termination shall be executed at a single-point earth reference to reduce noise coupling. Power isolation is mandatory during module replacement to preserve backplane integrity and prevent scan disruption.