Operation
3-4
3162-A2-GB20-40
August 2000
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.
