Allen-Bradley 1746-NO8I SLC 500 Analog Output Module

Allen-Bradley 1746-NO8I SLC 500 8-Channel Analog Output Module

Product Introduction

The Allen-Bradley 1746-NO8I significantly enhances SLC 500 control systems that demand multiple analog control points. This Analog Output Module provides eight independent current output channels, and each channel delivers a 0 to +20 mA signal. Therefore, it suits applications that need to drive numerous modulating devices, such as valves, actuators, and chart recorders, from a single chassis slot. Its compatibility with both fixed and modular SLC 500 hardware offers substantial flexibility for system designers. Moreover, the 1746-NO8I incorporates advanced features like programmable range settings and diagnostic capabilities, making it a dependable choice for complex automation tasks.

Technical Specifications

The 1746-NO8I excels in precision and performance within demanding industrial environments. It features eight (8) single-ended output channels, and all provide a standard current output range of 0 to +20 mA. For signal conversion, the module utilizes a high-resolution 16-bit digital-to-analog converter, which ensures exceptional control granularity over the connected field devices. Its update time is highly efficient, with all channels refreshing rapidly.

Additionally, this module boasts a field-wiring-to-backplane isolation rating of 500 Volts DC, which protects the processor and chassis from potential electrical faults. The 1746-NO8I also supports a Class 3 operating mode, enabling access to advanced features such as channel ramping, limit alarms, output clamping, and various data scaling options, simplifying ladder logic design.

Mechanical & Environmental Parameters

This SLC 500 module withstands the conditions of a typical industrial control cabinet. It comes in an open-type enclosure, and you can mount it in any 1746 chassis slot except slot 0. The module's ambient operating temperature ranges from 0 to 60 degrees Celsius, ensuring reliable performance even in warm environments. It also tolerates a non-condensing relative humidity of 5 to 95% for both operation and storage. For status monitoring, the 1746-NO8I includes a green module status indicator and eight green channel status LEDs, one for each output, providing immediate visual feedback on operational health.

Installation & Power Considerations

Installing the 1746-NO8I requires careful attention to ensure proper operation. First, select an appropriate slot in the SLC 500 chassis, avoiding slot 0. Before handling the module, take electrostatic discharge (ESD) precautions, such as touching a grounded object and wearing an approved wrist strap. The module offers flexibility in its power source selection through an internal jumper (J4). You can set the jumper to draw all power from the backplane, which consumes 120 mA at 5V DC and 250 mA at 24V DC. Alternatively, set the jumper to the EXT position to draw its 24V DC power from an external N.E.C. Class 2 supply, reducing backplane loading. In this configuration, the 24V DC backplane current draw drops to 0 mA, while the 5V DC draw remains at 120 mA. IMPORTANT: When using an external supply, do not use the 24V DC user power terminal on the chassis power supply; instead, use a separate, dedicated source.

Furthermore, the module features a removable terminal block (RTB), which simplifies wiring and module replacement. For wiring, use shielded, twisted-pair cable such as Belden 8761 or an equivalent, with a maximum wire size of 14 AWG. You may terminate a maximum of two wires per terminal, and the recommended terminal screw torque is 7 to 9 in.-lb. Always remember that this module does not support removal under power. Removing it while energized can cause electrical arcing, potentially damaging the module and other system components.

Configuration & Operating Modes

The 1746-NO8I offers significant configuration flexibility to suit various application requirements. It operates in two primary modes: Class 1 and Class 3. Class 1, the default mode, provides basic data output with no user scaling and remains compatible with the older 1746-NO4 module. In this mode, the module uses a fixed data format where a value of 0 corresponds to 0 mA and 32764 corresponds to 21 mA. To configure the module for Class 1 operation, simply assign it to a slot using the I/O Configuration in RSLogix 500.

Class 3 provides access to the module's full set of advanced features. This mode allows you to select engineering units, configure ramping, set clamping limits, enable alarming, and define safe-state options. The 1746-NO8I has specific module ID codes that you must enter into the software configuration. For the 1746-NO8I, the Class 1 ID code is 3527, and the Class 3 ID code is 12727. This advanced configuration works with RSLogix 500 version 6.10 and later.

Packaging & Logistics

This product listing covers the Allen-Bradley 1746-NO8I module exclusively. Your package will securely contain the module itself, complete with its removable terminal block (RTB) for immediate installation. The module also includes a finger-safe cover for added safety during wiring. All necessary mounting hardware comes as per standard factory packaging. We ship all orders using trusted global carriers, including Fedex, UPS, or DHL, guaranteeing prompt and trackable delivery to your facility.

Packaging List

• 1 x 1746-NO8I Analog Output Module

• 1 x Removable Terminal Block (RTB) (Catalog No. 1746-RT25G)

• 1 x Installation Instructions Guide

Frequently Asked Questions (FAQ)

1. What is the main function of the 1746-NO8I?
The 1746-NO8I converts digital commands from an SLC 500 PLC into precise 0-20 mA analog current signals across eight channels. These signals drive field devices like valves and actuators.

2. How do I power the 1746-NO8I module?
You can power the module via the backplane or an external 24V DC supply. Use jumper J4 to select the power source. Set it to the RACK position to draw all power from the backplane, or the EXT position to use an external supply for the 24V power.

3. What is the difference between Class 1 and Class 3 operation?
Class 1 provides basic data output compatible with older 4-channel modules. Class 3 unlocks advanced features like user scaling, ramping, clamping, and alarming, providing greater control and flexibility.

4. What is the resolution of the 1746-NO8I?
The 1746-NO8I provides a high-resolution output of 16 bits. This ensures very fine control over the output signal, allowing for precise adjustments to the connected process instruments.

5. Can I remove the 1746-NO8I while the system is powered on?
No, you must never remove or install this module under power. Doing so can cause electrical arcing, potentially harming the module and other components. Always power down the chassis first.