Actuator Driver Pwa (A2) - Sun Microsystems Enterprise Tape Library 7/3500 Field Service Manual

Actuator Driver PWA (A2)

The actuator driver PWA drives the library robotic mechanisms by using low-level
signal commands. This PWA provides the following functions:
Shunt over-voltage protection (OVP) regulator
X-axis motor interface
Y-axis motor interface
Extension motor interface
Tape drive handle motor interface
Load port lockout solenoid interface
Shunt OVP
The shunt OVP regulator on the actuator driver board serves two functions:
Over-voltage protection of the motor power supply
Rapid discharge of +48 VDC and +24 VDC in the event of a fault condition
The OVP regulator "shunts" to ground any regenerated current that create a voltage
fluctuation above 51.5 VDC. Therefore, the +48 VDC supply line is regulated to
below +51.5 VDC. A fault condition results in the rapid discharge of the motor bus.
For example, a fault condition occurs when the door is opened, the STOP switch is
pressed, the microprocessor watchdog times out, or when the +5V or +12V is out of
regulation. A fault condition immediately shuts down all actuators and rapidly
discharges the motor bus voltages within 100 milliseconds.
X-Axis Motor Interface
The x-axis motor interface on the actuator driver PWA receives open-loop low-level
step, direction, and current commands from the robotics controller. This PWA
amplifies and synthesizes the command signal to provide a high current two-phase
microstepping drive signal to the x-axis stepper motor.
Y-Axis Motor Interface
The y-axis motor interface on the actuator driver PWA receives open-loop low-level
step, direction, and current commands from the robotics controller. The PWA
amplifies and synthesizes the command signal to provide a high current two-phase
microstepping drive signal to the y-axis stepper motor.
8 Sun Enterprise Tape Library 7/3500 Field Service Manual • July 1997