Release Notes

Scalar 218 Theory of Operation
adic Service Procedure 63-1181-01 Rev A 5
Media Handling Mechanism
This section controls all movement of media within the 218. It is used to pick and place media between the
DLT drives and the 18 cartridge locations. The Media Handling Mechanism components include the
Media Picker, X Stepper Motor, X carriage, carriage rails, and associated drive belts and sensors.
Media Picker
Entry/Exit Port
The pass-through Entry/Exit Port allows the Media Picker to pick or place data cartridges from/to the
storage slots and drives without needing an additional media handling mechanism or having to rotate a
cartridge. Cartridge Sensors are mounted in both openings of the Entry/Exit Port. These sensors
monitor the position of the data cartridge. If the cartridge is not fully positioned in the Cartridge Gripper
Assembly, the Picker Processor informs the Main Processor via the Motion Processor. The
Motion Processor will prevent all movement of the Media Picker until the incorrectly positioned
cartridge is cleared.
Cartridge Gripper Assembly
The cartridge gripper assembly is an integral part of the Media Picker. The gripper is engaged by a DC
motor (Gripper Motor) which is controlled by the robotics firmware. The Gripper Motor servo control
senses torque, when a preset torque level is reached, the gripper stops.
Picker-Home Sensors
The Picker Home Sensors tells the robotics controller when the Media Picker is positioned at the
exact home position. To have a starting reference position the Media Picker must start after a reset from
the Picker-Home position (at the left side of the carriage rails). This position is determined by the Picker-
Home Sensor, which report its status to the robotics controller. It is the only time that the controller has
an indication of the physical position of the Media Picker. All other positions are referenced from this
point.
Barcode Reader
The Barcode Reader is used to scan barcode labels on the data cartridges located in the storage slots.
This information is passed to the application software via the SCSI bus, which stores it in its cartridge
inventory log. The barcode codes supported by the Scalar 218 are: Code 3 of 9 and Code 128.
The Barcode Reader uses a Charge Coupled Device (CCD) sensor and a Light Emitting Diode (LED)
light source. The depth of field ranges from approximately 2 inches up to 20 inches (barcode size
dependent). The red light from the LED appears as a red stripe on the barcode. The scanner is positioned
so that the light is reflected back to the CCD for reading. The Barcode Reader receives its trigger from
the Picker Processor, and outputs the scanned barcode data over the serial bus.