The 1791-8AC module is a Block I/O module that has been manufactured and introduced to the machine control industry by Allen-Bradley/Rockwell Automation into the Allen-Bradley 1791 product line of Block I/O modules. This Block I/O module comes with both inputs and outputs and it also provides isolation between both of these groups. This isolation also works between the power supply and the RIO and between the circuit groups and the logic group. This module comes with removable terminal strips and channel indicators that show the current status of each input and output. The Allen-Bradley 1791-8AC Block I/O module comes with an internally protected external power source that provides a voltage range of 85 to 132 Volts AC.

The input specifications of the Allen-Bradley 1791-8AC Block I/O module are a nominal input current of 11 milliamps, a nominal input voltage of 120 Volts AC, an input impedance of 15 kiloohms, an input signal delay of 1 millisecond, and a frequency of 47 to 63 Hertz. The output specifications of the Allen-Bradley 1791-8AC Block I/O module are an output voltage range of 20 to 132 Volts AC, a current rating of 150 to 300 milliamps depending on the installation position of the module, a surge current of 10 Amps, and a minimum on-state current of 50 milliamps per output. In general, the module comes with 8 inputs and 8 outputs that are arranged in their respective groups. The module can be used in environments with an operating temperature range of 0 to 60 degrees Celsius and a relative humidity range of 5 to 95 percent without condensation. Overheating must be avoided.