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3-73160-A2-GB21-50 January 1997
Table 3-4
Data Port LEDs
Name
Color Meaning
DTR Green Monitors the state of interchange circuit CD (CCITT 108/1, /2) – Data Terminal Ready
received from the synchronous data DTE.
ON:
DTR is being asserted by the synchronous data DTE.
OFF:
DTR is not being asserted.
TXD Yellow Monitors activity on interchange circuit BA (CCITT 103) – Transmitted Data. This is the
data sent from the synchronous data DTE to the data port on the DSU/CSU.
ON:
Ones are being received from the synchronous data DTE.
OFF:
Zeros are being received from the synchronous data DTE.
CYCLING:
Both ones and zeros are being received from the synchronous data
DTE.
RXD Yellow Monitors activity on interchange circuit BB (CCITT 104) – Received Data. This is data
sent to the synchronous data DTE from the data port on the DSU/CSU.
ON:
Ones are being sent to the synchronous data DTE.
OFF:
Zeros are being sent to the synchronous data DTE.
CYCLING:
Both ones and zeros are being sent to the synchronous data DTE.
CTS Yellow Monitors the state of interchange circuit CB (CCITT 106) – Clear-to-Send sent to the
synchronous data DTE.
ON:
CTS is being asserted by the DSU/CSU.
OFF:
CTS is not being asserted.
RTS Yellow Monitors the state of interchange circuit CA (CCITT 105) – Request-to-Send received
from the synchronous data DTE.
ON:
RTS is being asserted by the synchronous data DTE.
OFF:
RTS is not being asserted.