The Allen-Bradley 1794-IA8 Flex I/O AC digital input module delivers a robust, high-value solution for monitoring AC sensors and switches. This module efficiently converts your 120V AC field signals into a logic level your processor can use. You can integrate this module into distributed control architectures using networks like DeviceNet and EtherNet/IP. It is the perfect choice for applications needing reliable discrete input monitoring in a compact form factor.
Product Procurement & Buyer Guide
Voltage & Power Compatibility
Ensure your system provides the correct AC voltage for the 1794-IA8. This module operates with a nominal voltage of 120 Volts AC. It supports an input range from 85 to 132 Volts AC at a frequency of 47 to 63 Hertz. The module draws a nominal current of 12 mA per channel. Your total system power budget must account for a maximum power dissipation of 4.5 Watts at 132V AC for this single module.
Input Characteristics & Point Density
This module features exactly 8 non-isolated inputs, which share a common return path. You must verify that the on-state voltage for your field device falls between 65V AC minimum and 132V AC maximum. The module detects an off-state condition when the field voltage drops below 43V AC. It requires a minimum on-state current of 7.1 mA to guarantee reliable signal detection.
Selecting the Correct Terminal Base
You must purchase a compatible terminal base unit for the 1794-IA8 to function. This specific module works with many 1794-TB terminal bases, including the 1794-TB3 and 1794-TBN. The terminal base provides the physical connection for field wiring. It also establishes the backplane connection that supplies 5V DC power and data to the module.
Environmental & Installation Tolerances
This module uses an open-style enclosure rated IP20 to protect against solid objects. You can mount this module securely on a standard DIN Rail. The 1794-IA8 operates reliably within an ambient temperature range of -20 to 55 degrees Celsius. It also withstands high humidity levels of 5 to 95 percent without condensation, making it suitable for many challenging plant floor environments.
Filter Time & Signal Processing
The module uses a hardware filter to create a stable digital signal from an AC waveform. The default filter time for an off-to-on transition is 8.4 milliseconds. The filter time for an on-to-off transition is longer at 26.4 milliseconds. This delay prevents false triggering from electrical noise or contact bounce, ensuring input data integrity.
