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.
