
Product Overview
Reliable digital signal acquisition is fundamental to the performance of industrial automation systems. The Allen-Bradley 1746-IV8 SLC 500 DC Input Module is a high-performance 8-point 24V DC digital input module designed for the SLC 500 PLC platform, providing fast and dependable monitoring of field input devices in a wide range of industrial applications.
The 1746-IV8 interfaces directly with DC field devices such as proximity sensors, photoelectric sensors, push buttons, selector switches, and auxiliary contacts. Installed in an SLC 500 chassis, the module communicates through the backplane with the PLC processor, allowing real-time acquisition of field signals for machine control, process automation, and production monitoring.
With its compact dimensions of 144.5 × 34.6 × 130.18 mm and lightweight 0.16 kg construction, the 1746-IV8 provides a space-efficient and reliable solution for expanding digital input capacity in both new installations and legacy SLC 500 systems.
Technical Specifications
| Parameter |
Details |
| Manufacturer |
Allen-Bradley |
| Model |
1746-IV8 |
| Product Type |
SLC 500 DC Input Module |
| PLC Platform |
SLC 500 |
| Input Points |
8 Digital Inputs |
| Input Voltage |
24 VDC (10–30 VDC Operating Range) |
| Input Type |
DC Sourcing Input |
| Points per Common |
8 |
| Nominal Input Current |
8 mA per Channel @ 24 VDC |
| Signal Delay |
8 ms (ON / OFF) |
| Backplane Current Consumption |
50 mA @ 5 VDC |
| Installation |
SLC 500 Chassis |
| Mounting |
Backplane Installation |
| Dimensions |
144.5 × 34.6 × 130.18 mm |
| Weight |
0.16 kg |
| Application |
Industrial Digital Signal Acquisition |
Product Features
The 1746-IV8 is engineered for dependable digital input processing in demanding industrial environments.
Key features include:
- Eight independent 24V DC digital input channels
- Fast response with 8 ms signal filtering
- Reliable detection of field device status
- Direct integration with SLC 500 PLC systems
- Compact single-slot module design
- Stable operation under continuous industrial workloads
- High electrical noise immunity
- Simple wiring and maintenance
Its robust design helps ensure accurate signal acquisition while improving overall machine reliability.
Working Principle
The 1746-IV8 functions as the digital input interface between field devices and the SLC 500 PLC processor.
When an external device such as a proximity sensor, push button, or limit switch changes state, a 24V DC input signal is applied to the corresponding input channel. The module detects the voltage change, filters electrical noise through its internal circuitry, and transfers the digital status to the PLC processor via the SLC 500 backplane.
The PLC then executes the user program based on the received input signals, allowing real-time control of machines and industrial processes.
Typical connected devices include:
- Proximity sensors
- Limit switches
- Push buttons
- Selector switches
- Photoelectric sensors
- Auxiliary relay contacts
Role in Industrial Automation Systems
The 1746-IV8 serves as the primary interface for receiving digital input signals from field devices.
| Function |
Description |
| Digital Signal Acquisition |
Receives on/off signals from field devices |
| Sensor Interface |
Connects industrial sensors to the PLC |
| Machine Monitoring |
Detects equipment operating status |
| Process Control |
Provides real-time input data for PLC logic |
| Automation Control |
Supports machine sequencing and safety logic |
| System Expansion |
Adds additional digital input capacity |
Industrial Applications
The Allen-Bradley 1746-IV8 is widely used in industrial automation and process control applications.
| Industry |
Typical Equipment |
| Manufacturing |
Automated production lines |
| Packaging |
Filling, sealing, and labeling machines |
| Automotive |
Robotic assembly systems |
| Food & Beverage |
Conveyor and packaging equipment |
| Pharmaceutical |
Process automation systems |
| Material Handling |
Conveyor control systems |
| Water Treatment |
Pump and valve monitoring |
| General Industry |
PLC-based machine control systems |
Its dependable input processing makes it suitable for virtually any industrial application requiring digital signal monitoring.
Installation and System Integration
Proper installation ensures reliable signal acquisition and long service life.
Recommended installation procedures include:
- Install the module into an available SLC 500 chassis slot.
- Verify adequate backplane power capacity.
- Connect field input devices using the appropriate wiring configuration.
- Ensure proper DC power supply polarity.
- Check wiring terminals for secure connections.
- Verify input indicators during commissioning.
- Test all field devices before system startup.
Correct installation minimizes wiring faults and ensures stable PLC operation.
Compatible System Components
The 1746-IV8 integrates seamlessly with other SLC 500 automation components.
| Compatible Component |
Function |
| SLC 500 Processor |
Executes PLC control logic |
| SLC 500 Chassis |
Houses the I/O modules |
| 1746-OB8 Output Module |
Digital output control |
| 1746-OW16 Relay Output Module |
Relay switching applications |
| 1746-NI4 Analog Input Module |
Analog signal acquisition |
| Human Machine Interface (HMI) |
Operator monitoring and control |
| Industrial DC Power Supply |
Provides 24V DC operating power |
Together, these components create a complete and scalable industrial automation solution.
Recommended Alternative Models
| Model |
Product Type |
Key Feature |
Typical Application |
| 1746-IV8 |
8-Point DC Input Module |
24V DC sourcing inputs |
General machine control |
| 1746-IB8 |
8-Point DC Input Module |
Sink input configuration |
Standard automation systems |
| 1746-IB16 |
16-Point DC Input Module |
Higher input density |
Large-scale equipment |
| 1746-IV16 |
16-Point DC Input Module |
24V DC sourcing inputs |
Expanded digital input systems |
| 1746-ITV16 |
Fast DC Input Module |
High-speed response |
Motion control and high-speed automation |
Key Advantages
- Eight reliable 24V DC digital input channels
- Fast and stable signal processing
- Excellent electrical noise immunity
- Compact single-slot design
- Easy integration with SLC 500 PLC systems
- Reliable industrial-grade construction
- Simplified installation and maintenance
- Ideal for machine control and process automation
Technical FAQs
What is the Allen-Bradley 1746-IV8 used for?
The 1746-IV8 is used to receive 24V DC digital signals from field devices such as sensors, push buttons, limit switches, and auxiliary contacts, allowing the SLC 500 PLC to monitor machine status and execute control logic.
How many input channels does the module provide?
The module provides 8 independent digital DC input channels, making it suitable for small and medium-sized automation systems.
Which field devices can be connected to the 1746-IV8?
It supports a variety of industrial devices, including proximity sensors, photoelectric sensors, push buttons, selector switches, relay contacts, and limit switches.
Which PLC platform is compatible with this module?
The 1746-IV8 is specifically designed for the Allen-Bradley SLC 500 programmable controller platform.
Conclusion
The Allen-Bradley 1746-IV8 SLC 500 DC Input Module is a dependable digital input solution designed to provide accurate signal acquisition for industrial automation systems.
Featuring 8 digital input channels, 24V DC operation, compact dimensions of 144.5 × 34.6 × 130.18 mm, and a lightweight 0.16 kg design, the module delivers reliable performance, easy integration, and long-term operational stability.
Whether installed in manufacturing equipment, packaging machinery, process automation systems, or material handling applications, the 1746-IV8 offers an efficient and reliable solution for expanding digital input capability while maintaining the high performance expected from the Allen-Bradley SLC 500 platform.