The 1774-LD2 arithmetic module by Allen-Bradley features processor input and output ports that are packaged together in a single unit. The unit comes with a processor whose core function is ensuring the control and supervision of all the module's operations. It is designed with an internal communication platform in the form of an internal bus that transmits information to the processor and the unit's memory. The 1774-LD2 module comes as a single slot processor module that is used for controlling the program execution as well as for the management of functionalities. To achieve an efficient arithmetic capability, the 1774-LD2 module comes with over 70 programming instructions, making the unit able to achieve more power. To ensure the efficient use of the microprocessor time, the 1774-LD2 module comes with high-speed program scanning. Therefore, the 1774-LD2 module processes only the parts of the control program that are currently needed. The different program control instructions include the JMP, JSR, and MCR instructions.

The 1774-LD2 module features a timed interrupt routine, allowing the users to react to any major faults. This is made possible through stopping the processor to avoid faults. The 1774-LD2 module features an on-board diagnostic mechanism. This ensures easy monitoring and simplified troubleshooting in the case of a fault. The 1774-LD2 module should not be inserted into the PLC-3 main processor chassis. To provide an effective execution, the unit features a processor module and it uses up to four AMD bit-slice microprocessors. The unit ensures high-speed program scanning and this means that it is able to achieve a quick determination of the current status. The unit is built to ensure high-speed I/O processing, with no backplane access needed. The memory configuration features an effective approach for handling a wide variety of applications.