The Allen-Bradley 1746-IV8 is a high-performance digital input module engineered for the SLC 500 programmable logic controller platform. This module provides eight discrete input channels designed to process 24V DC signals from field-side devices such as proximity sensors, limit switches, and operator pushbuttons. As a current-sourcing module, it is optimized for integration with sinking-type (NPN) field devices.
Nominal input voltage of 24V DC with an operating range of 10-30V DC.
Integrated signal filtering with a consistent 8 ms delay for both ON and OFF transitions to mitigate noise and contact bounce.
Individual front-panel LED indicators for real-time status monitoring of each channel.
Compact SLC 500 form factor for efficient rack mounting.
Applications
This module is widely utilized in industrial automation environments for monitoring the state of binary field devices. It is suitable for control systems in manufacturing, material handling, and process automation where reliable 24V DC signal acquisition is required.
Technical Specifications
Brand
Allen-Bradley
Series
SLC 500
Module Type
Digital DC Input (Sourcing)
Input Points
8 (1 group of 8)
Nominal Voltage
24V DC
Voltage Range
10-30V DC
Off-State Voltage (Max)
5.0V DC
Off-State Current (Max)
1 mA
Nominal Input Current
8 mA @ 24V DC
Signal Delay
8 ms (ON/OFF)
Backplane Current (5V)
50 mA
Operating Temperature
0 to 60 degC
Installation Guidelines
Ensure the PLC rack is powered down before inserting or removing the 1746-IV8 module to prevent electrical damage.
Verify that the module is fully seated in the SLC 500 chassis and secured with the top and bottom mounting screws.
Use shielded cabling for input signal runs to minimize electromagnetic interference (EMI) in high-noise environments.
Maintain proper ventilation in the control cabinet to ensure the module operates within the specified temperature range of 0 to 60 degC.
Adhere to standard ESD (Electrostatic Discharge) handling procedures when touching the module circuitry.
FAQ
What does it mean that this is a current-sourcing module? A current-sourcing module provides the positive voltage (24V DC) to the field device. Therefore, it is intended to be used with sinking-type (NPN) sensors or switches that connect the signal line to ground when activated.
Can I use this module with 120V AC inputs? No, the 1746-IV8 is specifically designed for 24V DC applications. Using it with AC voltage or voltages outside the 10-30V DC range will cause permanent damage to the module.
