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Description
The Allen-Bradley 1746-IA4 is a discrete AC input module engineered for the SLC 500 programmable logic controller system. This module provides four (4) isolated input channels rated for 100/120V AC operation. It is designed for industrial environments requiring reliable signal detection from field devices such as limit switches, pushbuttons, or auxiliary contacts. By providing a compact, four-point interface, it allows for efficient and cost-effective I/O expansion in smaller control panels or specific machine-level applications.
Features
- Four (4) independent AC input channels.
- Standard operating voltage range of 85–132V AC.
- Integrated hardware signal filtering with 35 ms ON and 45 ms OFF delays to mitigate contact bounce.
- Front-panel LED indicators for real-time status monitoring of each input channel.
- Low backplane power consumption (35 mA at 5V DC).
- Designed for seamless integration into the SLC 500 chassis backplane.
Applications
The 1746-IA4 is suitable for a wide range of industrial automation tasks, including machine control, process monitoring, and general-purpose discrete signal acquisition. It is commonly utilized in systems where AC-powered field devices must interface directly with the SLC 500 controller.
Technical Specifications
| Brand |
Allen-Bradley |
| Product Line |
SLC 500 |
| Module Type |
Digital AC Input Module |
| Number of Inputs |
4 |
| Voltage Category |
100/120V AC |
| Operating Voltage Range |
85–132V AC |
| Nominal Input Current |
12 mA @ 120V AC |
| Max. Off-State Voltage |
30V AC |
| Max. Off-State Current |
2 mA |
| Backplane Current (5V DC) |
35 mA |
| Backplane Current (24V DC) |
0 mA |
| Thermal Dissipation |
0.175 W (Min) to 1.3 W (Max) |
| Operating Temperature |
0 to 60 degC (32 to 140 degF) |
Installation Guidelines
- Always remove power from the SLC 500 chassis before inserting or removing any I/O module to prevent electrical damage.
- Ensure the module is fully seated in the chassis slot and the locking tab is engaged to maintain a secure connection to the backplane.
- Use appropriate shielded cabling for input signals to minimize interference from high-voltage lines or EMI sources.
- Maintain proper ventilation within the enclosure to ensure the module operates within its specified temperature range (0 to 60 degC).
- Verify that field wiring polarity and voltage levels match the module specifications before applying power.
FAQ
What is the primary function of the 1746-IA4?
The 1746-IA4 is a digital input module that converts 120V AC signals from field devices into logic levels compatible with the SLC 500 processor.
Does this module require external power?
The module receives its internal logic power from the SLC 500 backplane. The field-side inputs are powered by the 120V AC source connected to the field wiring terminals.
Can this module be used with DC signals?
No, the 1746-IA4 is specifically designed for AC signals. Using it with DC voltage may result in incorrect operation or damage to the module.
