Operation
Xerox LS 3270
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3. Operation of the Xerox LS 3270
The Xerox LS 3270 top panel has been designed to register the
operation of the box via the following indicator LEDs :
• CU (contact to Control Unit)
• PAR (parallel input)
See the illustration in the section Knowing the Front Panel for the
position of the LEDs.

3.1. Indicators of the Xerox LS 3270

CU (Contact with Control Unit)

This indicator LED has 3 states:
State Indication
ON Contact with the control unit.
BLINKING 1. Contact with the control unit, and data pending
in the Xerox LS 3270 buffer.
2. Indicates that the address switch has been
activated and the box is ready to enter on-line
HEX dump mode
OFF No contact to the control unit, or the contact has
been broken for more than 1 minute.

PAR (Parallel input)

The indicator LED has 2 states:
State Indication
ON Indicates that the box is processing data from the
Centronics parallel port
OFF Indicates that the box is idle or processing data
from the coax input