The Allen-Bradley 8520 CNC Controller series is a series of digital amplifiers. This series features a wide range of CNC parts from 9 smaller series of CNC parts. The module enclosures of the 8520 CNC controllers are compatible with the system, power supply, CPU boards, and the servo modules. Additionally, the component enclosures are well-matched with the digital and analog servo modules. One of the leading products in the 8520 CNC Controllers series is the 8520-32EMB controller, which has an enhanced motherboard attached to its enclosure at the back wall and a CPU that is also connected to it to improve the processing of all the control and software functions. This motherboard features red and green LEDs for indicating the overall status of the operations and power of the controller. Additionally, signals are sent to the 8520-32EMB enhanced motherboard controller through the fiber optic input and output rings in a connection that provides serial communication to the controller. 

The Allen-Bradley 8520 CNC Controllers all feature jumper settings that help with the configuration of the peak current of the drives as a percentage of the RMS. This is known as the AMP functionality and it enables the operators to tell the controller how to configure the amplifier. However, it is essential to set this parameter so that it aligns with the settings of the amplifier jumper to allow the controller to perform the torque calculations correctly. The tools and the program offsets are saved in the RAM which is part of the motherboard. In the case of a hardware failure, the motherboard must be replaced by lining it up with the board through guide tracks on the top and bottom of the enclosure panels on the Allen-Bradley 8520 CNC Controller.