Allen-Bradley 1746-NI4/A — 4-Channel Analog Input Module | SLC 500 Platform
Engineering Background
The Allen-Bradley 1746-NI4/A is a dedicated analog input module engineered for the SLC 500 modular chassis family. Designed by Rockwell Automation, it provides four independently configurable analog input channels capable of accepting voltage and current signals from field transmitters, sensors, and transducers. The module integrates directly into the SLC 500 backplane, communicating with the SLC 5/01, 5/02, 5/03, 5/04, and 5/05 processors via the standard I/O chassis interface without requiring external signal conditioning hardware.
Product Positioning
Targeted at process control, machine automation, and legacy system maintenance applications, the 1746-NI4/A occupies a critical role in installations where SLC 500 infrastructure remains the backbone of production. For procurement engineers managing installed-base continuity, this module represents a proven, specification-matched replacement that eliminates re-engineering risk and minimizes downtime exposure.
Complete Technical Specifications
- Catalog Number: 1746-NI4/A
- Series: A
- Platform: Allen-Bradley SLC 500
- Number of Input Channels: 4 (independently configurable)
- Input Signal Types: ±10 VDC (voltage) | 4–20 mA (current)
- Resolution: 12-bit (1 sign bit + 11 data bits)
- Input Impedance (Voltage Mode): ≥ 100 kΩ
- Input Impedance (Current Mode): 249 Ω
- Data Format: Two’s complement integer (–2048 to +2047 counts)
- Conversion Rate: ~5 ms per channel (20 ms total, 4 channels)
- Accuracy: ±0.5% of full scale at 25°C
- Operating Temperature: 0°C to +60°C (32°F to 140°F)
- Storage Temperature: –40°C to +85°C
- Relative Humidity: 5% to 95% non-condensing
- Backplane Current Draw: 75 mA @ 5 VDC
- Power Dissipation: 0.375 W (typical)
- Isolation: 1500 VAC (channel-to-backplane)
- Wiring: Removable terminal block (RTB), 3-wire per channel
- Enclosure Rating: Open-style (IP20 equivalent)
- Agency Certifications: UL Listed, CE Marked, CSA Certified
- Dimensions (H × W × D): Single-slot SLC 500 module form factor
- Weight: Approx. 200 g
Proven Application Environments
- Process Industries: Oil & gas flow measurement, chemical dosing control, water treatment level monitoring
- Discrete Manufacturing: Tension control, position feedback from analog encoders, temperature loop inputs
- HVAC & Building Automation: Pressure transducer inputs, chiller control loops, VAV damper position feedback
- Food & Beverage: Load cell signal acquisition, fill-level monitoring, conveyor speed reference
- Legacy System Maintenance: Direct drop-in replacement for existing SLC 500 installations without processor reprogramming
Engineering Advantages
- Per-Channel Configurability: Each of the 4 channels is independently set for voltage or current mode via jumper selection — no channel interdependency.
- High Isolation Barrier: 1500 VAC channel-to-backplane isolation protects the processor from field-side transients and ground loops.
- Removable Terminal Block: RTB design allows field wiring to remain intact during module swap, reducing maintenance time and wiring error risk.
- Deterministic Scan Time: Fixed 5 ms/channel conversion rate integrates predictably into SLC 500 ladder logic scan cycles.
- Native Backplane Communication: No gateway, adapter, or protocol converter required — direct SLC 500 I/O chassis integration.
- Compact Single-Slot Footprint: Maximizes chassis slot utilization in space-constrained control panels.
System Architecture & Signal Flow
Field transmitters (4–20 mA loop-powered or ±10 VDC sourced) connect to the 1746-NI4/A via the removable terminal block. Each channel’s input is routed through a multiplexer to a shared 12-bit ADC. Converted digital values are stored in the SLC 500 input image table (I-file) and are available to the processor on every I/O scan. The processor reads channel data as signed integers in the range –2048 to +2047, which ladder logic scales to engineering units (e.g., 0–100% flow, 0–150°C temperature) using the SCL or CPT instruction.
Jumper J1–J4 on the module PCB select voltage (V) or current (I) mode per channel. Configuration is hardware-defined and does not require RSLogix 500 software parameter changes — the processor reads the module type automatically via the backplane.
Sourcing & Quality Verification
- Source: Decommissioned industrial surplus, authorized distributor overstock, and factory-sealed new-old-stock (NOS)
- Inspection Protocol: Visual inspection (housing, terminal block, label integrity), functional power-on test, backplane communication verification
- Firmware/Series Verification: Series A designation confirmed prior to shipment — no mixed-series substitution
- Packaging: Anti-static bag + foam-lined carton; humidity indicator card included for long-transit shipments
- Documentation: Allen-Bradley publication 1746-UM005 (User Manual) available upon request
- Warranty: 90-day operational warranty against DOA and latent defects
Procurement Process
- Step 1 — Inquiry: Submit your required quantity and delivery timeline via the order form or email support@konmask.com
- Step 2 — Stock Confirmation: Konmask confirms available stock, series, and condition within 1 business day
- Step 3 — Quotation: Formal quotation issued with unit price, shipping cost, and lead time
- Step 4 — Payment: T/T bank transfer, PayPal, or trade-term arrangements (FOB Xiamen available)
- Step 5 — Shipment: DHL / FedEx / UPS express with tracking; EXW/FOB/CIF Incoterms supported
- Step 6 — After-Sales: Technical support and warranty claims handled directly by Konmask engineering team
Technical FAQ
Q: Is the 1746-NI4/A compatible with all SLC 500 processors?
A: Yes — it is compatible with SLC 5/01, 5/02, 5/03, 5/04, and 5/05 processors in any SLC 500 modular chassis (1746-A4, A7, A10, A13).
Q: Can I mix voltage and current channels on the same module?
A: Yes. Each channel is independently jumper-configured for ±10 VDC or 4–20 mA. All four channels can be set differently.
Q: What is the difference between Series A and later series?
A: Series A is the original release. Later series (B, C) introduced minor hardware revisions. For most applications, Series A is functionally equivalent. Confirm with your system integrator if your application has strict series requirements.
Q: Does this module require external power supply for current loop transmitters?
A: The 1746-NI4/A does not supply loop power. 2-wire (loop-powered) transmitters require an external 24 VDC loop supply. 4-wire transmitters are self-powered.
Q: What RSLogix 500 configuration is required?
A: The module is auto-identified by the SLC 500 processor. No special I/O configuration file is required. Scaling of raw ADC counts to engineering units is performed in ladder logic using SCL, CPT, or MVM instructions.
Q: Can Konmask provide a test report before shipment?
A: Yes. Functional test reports are available upon request for orders of 3+ units. Contact support@konmask.com to arrange pre-shipment inspection.
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