Product Overview

The Allen-Bradley 1746-NI8 is an analog input module for the SLC 500 system. This module provides eight non-isolated differential input channels. Each channel is individually selectable for voltage or current input. The Allen-Bradley 1746-NI8 occupies a single slot in the SLC 500 chassis. Users trust this module for time-sensitive applications requiring fast analog conversion and high accuracy.

Technical Specifications

The 1746-NI8 delivers accurate analog conversion with programmable filtering. Below are the complete technical details.

General Specifications

• Manufacturer: Rockwell Automation for industrial control reliability.

• Brand: Allen-Bradley for SLC 500 compatibility.

• Part Number: 1746-NI8 for precise identification.

• Series: SLC 500 programmable controller family.

• Module Type: Analog I/O Module (8-channel analog input).

• UPC: 10662072678036 for universal product identification.

• UNSPSC: 32151705 for classification.

• Chassis Location: Any I/O module slot except slot 0.

• Compatibility: Fixed or modular style hardware.

• Processor Compatibility: SLC 5/01, 5/02, 5/03, 5/04, and 5/05.

Input Channel Specifications

• Number of Inputs: Eight (8) non-isolated differential inputs.

• Input Signal Category: -20 to +20 mA or -10 to +10V DC.

• Voltage Input Types: 10V DC, 1-5V DC, 0-5V DC, 0-10V DC.

• Current Input Types: 0-20 mA, 4-20 mA, ±20 mA, 0-1 mA.

• Channel Configuration: User-selectable per channel via DIP switch.

• Input Impedance (Current): 250 Ohms.

• Input Impedance (Voltage): High impedance.

• Wiring Type: Single-ended or differential input per channel.

• Wire Size: 14 AWG maximum.

• Recommended Cable: Belden 8761 or similar.

Conversion and Performance Specifications

• Conversion Type: Successive approximation, switched capacitor.

• Resolution: 16 bits.

• Bandwidth: 1 to 75 Hertz programmable.

• Input Filter Frequencies: 1 Hz, 2 Hz, 5 Hz, 10 Hz, 20 Hz, 50 Hz, 75 Hz.

• Filter Type: Low-pass digital filter.

• Update Time: 6 milliseconds.

• Step Response: 0.75 to 730 milliseconds (filter dependent).

• Autocalibration: Continuous autocalibration performed.

Data Format Options

• Engineering Units: Direct process variable reading.

• Scaled for PID: For proportional-integral-derivative control.

• Proportional Counts: -32,768 to +32,767 range.

• Proportional Counts (User Defined): Class 3 only.

• 1746-NI4 Data Format: Compatibility mode.

Backplane Power Specifications

• Backplane Current (5 Volts): 200 milliamps.

• Backplane Current (24 Volts DC): 100 milliamps.

• Backplane Power Consumption (5V): 1 Watt maximum.

• Backplane Power Consumption (24V): 2.4 Watts maximum.

• Total Backplane Power: 14 Watts maximum.

• Thermal Dissipation: 3.4 Watts.

Isolation and Voltage Specifications

• Isolation Voltage: 750 Volts DC tested for 60 seconds.

• Isolation Voltage (AC): 530 Volts AC tested for 60 seconds.

• Common-Mode Voltage Range: -10 to +10 Volts.

• Common-Mode Maximum: 15 Volts between any two terminals.

Cable and Wiring Specifications

• Cable Type: Belden 8761 or similar recommended.

• Maximum Loop Impedance (Voltage Source): 40 Ohms.

• Maximum Loop Impedance (Current Source): 250 Ohms.

• Wires per Terminal: One or two 14 AWG wires.

• Maximum Cable Length: Standard SLC 500 analog cabling.

• Cable Part Number: 1492-ACABLE*C.

LED Indicators

• Number of LEDs: 9 green status indicators.

• Channel LEDs: One for each of 8 channels (input status).

• Module Status LED: One for overall module status.

• Diagnostic Capability: Quick troubleshooting and status monitoring.

Environmental and Hazardous Location

• Division 2 Hazardous Environment: Standard compliant.

• Operating Temperature: 0 to 60 degrees Celsius.

• Processor Class Support: SLC 5/01 (Class 1 only).

• Processor Class Support (Others): Class 1 and Class 3 for SLC 5/02, 5/03, 5/04.

Physical Specifications

• Removable Terminal Block: 18 positions for easy wiring.

• Terminal Block Benefit: Easy module replacement without rewiring.

• DIP Switches: Embedded for input signal type selection.

• Single Slot: Occupies one SLC 500 chassis slot.

Installation Guide

Follow these steps to install the Allen-Bradley 1746-NI8 correctly.

1. Power Down the Chassis: Turn off all power to the SLC 500 rack.

2. Locate an Available Slot: Find any I/O slot except slot 0.

3. Set DIP Switches: Configure each channel for voltage or current input.

4. Select Filter Frequency: Choose from 1 Hz to 75 Hz for each channel.

5. Insert the Module: Slide the 1746-NI8 into the slot carefully.

6. Secure the Module: Lock using the retaining clips at top and bottom.

7. Wire Removable Terminal Block: Connect analog signals to the 18-position RTB.

8. Use Belden 8761 Cable: Follow recommended cabling for best performance.

9. Check Loop Impedance: Verify 40 Ohms max for voltage, 250 Ohms for current.

10. Connect Single-Ended or Differential: Wire according to application needs.

11. Apply Power: Turn on the backplane power to the chassis.

12. Check LED Indicators: Verify 9 green status LEDs for proper operation.

13. Configure Data Format: Select Engineering Units, Scaled for PID, or Proportional Counts.

14. Set Processor Class: Configure Class 1 or Class 3 based on processor type.

15. Test Each Channel: Apply known signals and verify readings.

Installation Notes

• The module cannot go in slot 0 of the SLC 500 chassis.

• Successive approximation conversion provides 16-bit resolution.

• Update time is 6 milliseconds for all channels.

• Continuous autocalibration ensures measurement accuracy.

• The removable terminal block allows easy module replacement.

Packaging List

This unit ships as a new and original product.

• Allen-Bradley 1746-NI8 Analog Input Module

• Removable terminal block (18-position)

• Product data sheet with DIP switch settings

• Anti-static factory packaging bag

Frequently Asked Questions (FAQ)

1. How many analog input channels does the 1746-NI8 provide?
The Allen-Bradley 1746-NI8 provides eight non-isolated differential input channels. Each channel is individually selectable for voltage or current.

2. What filter frequencies are available on this analog module?
The 1746-NI8 offers programmable filter frequencies at 1, 2, 5, 10, 20, 50, and 75 Hz. Step response ranges from 0.75 to 730 milliseconds depending on filter selection.

3. What is the resolution and update time of the 1746-NI8?
The Allen-Bradley 1746-NI8 has 16-bit resolution. The update time is 6 milliseconds for all eight channels.

4. Which SLC 500 processors are compatible with this module?
The 1746-NI8 works with SLC 5/01, 5/02, 5/03, 5/04, and 5/05 processors. Note that SLC 5/01 only operates as Class 1.

5. Can I replace the 1746-NI8 without rewiring my field devices?
Yes, the Allen-Bradley 1746-NI8 features a removable terminal block. You can replace the module without disconnecting field wiring.