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3. Operation
3-8
February 2001 3160-A2-GB21-90
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.