Allen Bradley 8520-PX-ASM3-EXEC2-63M Analog Servo Module for 8520 CNC Systems

The Allen-Bradley 8520-PX-ASM3-EXEC2-63M is a 3-axis analog servo module for the 8520 CNC controller series. This module belongs to the series 9 CNC PAL family of switches and is designed to provide analog command signals to servo amplifiers for precise machine motion control. The 8520 CNC series includes a wide range of CNC parts, system power supplies, CPU boards, and servo modules in a modular enclosure architecture.

Technical Specifications

The 8520-ASM3 provides 3 axes of motion control with an output voltage range of +/-10V. The output offset voltage is 500mV maximum. The resolution is 1.22mV and the sampling frequency is 500Hz. Maximum output current is 5mA. The conversion time is 8.25ms with gain error of +/-1 LSB maximum. The analog output driver is single ended. The 8520-ASM3 has two analog drive configurations: a mill configuration supporting three axes of control, and a lathe configuration supporting two axes plus an open-loop spindle with position feedback.

System Integration and Installation

The module enclosures of the 8520 CNC controllers are compatible with the system power supply, CPU boards, and servo modules. The component enclosures are well-matched with digital and analog servo modules. The 8520-ASM3 is installed by aligning the board with guide tracks on the top and bottom of the enclosure panels. The positioning and velocity data is sent to the switch from the control unit, where the module processes the data to produce the signals that drive the motors in the corresponding direction.

Configuration and Parameter Setup

All 8520 CNC controllers feature jumper settings to configure the peak current of the drives as a percentage of the RMS, known as the AMP functionality. Operators can tell the controller how to configure the amplifier. It is essential to set this parameter to align with the amplifier jumper settings to allow the controller to perform torque calculations correctly. Tools and program offsets are saved in RAM which is part of the motherboard.

Applications and Compatibility

The 8520-ASM3 analog servo module is used in 8520 CNC systems for machine control in both mill and lathe configurations. The mill configuration provides three axes of control with each axis having its individual servo control and a feedback device. The lathe configuration provides two axes of control with each axis having a servo motor, a feedback device, and an open-loop spindle with position feedback. The servo amplifier amplifies the signal from the servo module to drive the servo motors.

Electrical Specifications

Output offset voltage maximum is 500 mV. Maximum output current is 5 mA. Load range is 2 kOhms to infinity. The unit has a weight of 1.88 lbs (0.85 kg). Load capacity performance is according to the product specifications. The output driver type is single ended.

Conclusion

The Allen Bradley 8520-PX-ASM3-EXEC2-63M analog servo module provides +/-10V output for up to 3 axes in 8520 CNC systems. With a sampling frequency of 500 Hz and single-ended output drivers, it supports precise motion control for both mill and lathe configurations in legacy CNC machinery.