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1.6:
PAPER-OUT DETECTION
A photoelectric sensor is employed to detect the absence of paper. It is attached to the
lower-paper guide which is mounted to the bottom side of the platen. The sensor is
constructed with an infrared light-emitting diode (ILED) mounted adjacent to a
phototransistor. If paper is present, light emitted by the ILED will reflect from the paper
and return to the phototransistor. If the paper is removed, no light will be reflected and
printing will cease.
A paper out condition will cause the paper-out indicator on the operator panel to flash and
the bell will sound three times. The microprocessor will halt all printer activity and raise
BUSY until paper is loaded into the printer.
1.7:
BELL OPERATION
A piezoelectric transducer generates an audible tone upon receipt of the bell character. A
single bell, or tone burst, is produced by applying a 2 KHz square wave to the transducer.
The occurrence of a bell tone is not synchronized to any physical attribute of the printer
such as printhead or paper position.
Bells may also be generated locally in setup mode to prompt the operator when certain
errors have occurred. It also alerts the operator when the paper supply is depleted.
1.8:
OPERATOR CONTROL PANEL
A 16-key panel, or pad, is provided to enable the operator to define features which are
programmable or selectable. Certain keys are dedicated to specific machine functions such
as reset, paper advance, etc.
In addition to key switches, an LED display and several discrete LED's are located on the
control panel. The individual LED's are provided to indicate status such as on-line, paper-
out, etc. The 4-digit display; however, is general purpose in nature. In setup mode it is used
to show feature codes, feature status, and feature values. In normal mode, it displays the
location on the paper where the next line of print will occur. Certain diagnostics also
employ it for fault isolation. Refer to the Operator's Manual for a detailed description of
machine setup and control using the front panel.
1-3
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