Allen Bradley 1791-24B8 Series B I/O Module

Category

PLCs

Product Line

1791 Block I/O

Part Number

1791-24B8

UPC

612598124794

Weight

1.75 lbs (0.79 kg)

Voltage

24 Volts DC

Inputs per Block

24

Input On-state Voltage Range

10 to 30 Volts DC

Input On-state Current

11mA at 30 Volts max.

Input Off-state Voltage

5 Volts DC max.

Input Off-state Current

1.5mA min.

Outputs per Block

8

Output Voltage Range

10 to 30 Volts DC

External Power

19.2 to 30 Volts DC

Product Lifecycle Status*

Discontinued/Obsolete

The Allen-Bradley 1791-24B8 is an I/O module with 24 inputs and 8 outputs. It has 24 inputs in 3 groups of 8 per block and an ON-state input rating of 10 to 30 Volts DC voltage and a 2.5 milliamps minimum input current at 11 Volts which maxes out at 11 milliamps at 30 Volts DC. It has a maximum ON-state input voltage of 5 Volts DC at 1.5 milliamps and an input impedance of 3.4. The 1791-24B8 has an input signal delay of 1 millisecond ON, 5 milliseconds OFF (fast), and 1 millisecond ON and 18 milliseconds OFF (slow).

The 1791-24B8 has an output rating of 500 milliamps/1Amps at 30 to 60 degrees Celsius with a vertical mounting and 250 to 500 milliamps at 30 to 60 degrees Celsius with a horizontal mounting. It has a current that surges at 3 Amps for 50 seconds that keeps recurring after 2 seconds. The 1791-24B8 has an output OFF-state current of 1 milliamps at a drop voltage of 1 Volts and 0.5 milliamps of current leakage. It has an external power supply with internal protection which supplies voltage in the range between 19.2 and 30 Volts DC at a current of 300 milliamps. The 1791-24B8 has a maximum thermal dissipation of 58.1 BTU/hour and a maximum power dissipation of 17.1 Watts. It has an operational temperature range between 0 and 60 degrees Celsius (32 and 140 degrees Fahrenheit) at a relative humidity of 5 to 95% non-condensing. The 1791-24B8 measures 176.5 millimeters x 68.8 millimeters x 98 millimeters (6.95 inches x 2.7 inches x 3.85 inches) and it weighs 1.02 kilograms (2.25 pounds).

Question

Answer

What is the Allen-Bradley 1791-24B8 used for?

The Allen-Bradley 1791-24B8 is a Block I/O module designed for distributed industrial I/O applications. It combines input and output functions into a compact unit for machine control and automation systems.

How many inputs and outputs does the 1791-24B8 provide?

The module provides 24 DC inputs and 8 DC outputs, allowing efficient signal handling for sensors, switches, and actuators in industrial environments.

What communication network does the 1791-24B8 support?

The 1791-24B8 is designed for Remote I/O communication, enabling integration with Allen-Bradley PLC systems and distributed control architectures.

What are the operating voltage specifications of the 1791-24B8?

The module typically operates with a 24V DC power supply for both input sensing and output control functions, making it suitable for standard industrial automation applications.

Is the Allen-Bradley 1791-24B8 still available?

The 1791-24B8 is considered a discontinued legacy product, but refurbished, surplus, and replacement units are still available from industrial automation suppliers and repair providers.

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