Specifications

3-5
Cisco AS5800 Operations, Administration, Maintenance, and Provisioning Guide
DOC-7810814=
Chapter 3 Operations
Verifying Modem Performance
Table 3-1 EIA/TIA-232 Signal State Behavior
Signal Signal Direction Purpose
Transmit Data (TxD) ——>
(Output)
DTE transmits data to DCE.
Receive Data (RxD) <——
(Input)
DCE transmits received data to DTE.
Request To Send (RTS) ——>
(Output)
DTE uses the RTS output signal to indicate if it can receive
characters into the Rx input buffer
1
.
The DCE should not send data to the DTE when DTR input is low
(no RTS).
1. The name RTS is illogical with the function (able to receive) due to historical reasons.
Clear To Send (CTS) <——
(Input)
DCE signals to DTE that it can continue to accept data into its
buffers.
DCE asserts CTS only if the DCE is able to accept data.
Data Terminal Ready (DTR) ——>
(Output)
DTE signals to DCE that it can continue to accept data into its
buffers.
DTE asserts RTS only if the DTE is able to accept data.
Data Carrier Detect (DCD) <——
(Input)
DCE indicates to DTE that a call is established with a remote
modem. Dropping DCD terminates the session.
DCD will be up on the DCE only if the DCE has achieved data
mode with its peer DCE (client modem).