The CompactBlock I/O 1791R modules are I/O blocks that are manufactured and designed by Allen-Bradley. This series of modules includes 5 different models, depending on the application requirements. Generally, this kind of block is used to expand a network. Among the 5 blocks that are available, there is the option to order 1 base module or 1 base module, including the expansion module. Several modules can be coupled together. These blocks communicate with different kinds of equipment and networks through I/O technology, including RIO communication. The Allen-Bradley CompactBlock I/O 1791R modules require an input power of 24 Volts DC. These blocks provide sinking input and outputs. The sinking input and output are in charge of providing the grounding needed for a safe machine. As a visual feature, the modules contain status indicators. These indicators show whether there is a failure or not. Communication indicators have also been added to the modules. 

The Allen-Bradley CompactBlock I/O 1791R modules have been designed to operate in Pollution Degree 2 rated environments. Even though these are enclosed pieces of equipment, a secondary enclosure must be added to provide the level of protection needed to both the modules and all of the connections. When adding an enclosure, a means of ventilation must be provided to avoid overheating. The maximum operating temperature rating goes from -40 to 85 degrees Celsius, and a humidity level of up to 90% is also recommended. When installing the Allen-Bradley CompactBlock I/O 1791R modules, these can be mounted on a DIN rail. These modules are sensitive to electrostatic discharge, so the technicians must be careful and the workstation needs to be prepared properly before the users begin to assemble the modules.