ds22-l100-041 Conexant Systems, Inc., ds22-l100-041 Datasheet - Page 29

• Manufacturer Part Number: ds22-l100-041
• Description: Cx84100-41/-23 Scxv.22bis Modem V.22bis Modem With Cx20493 Smartdaa? Line Side Device
• Manufacturer: Conexant Systems, Inc.

Table 3-2. CX84100 V.22bis Modem Pin Signal Definitions (Continued)
102339C
TXD#
RXD#
CTS#
RLSD#
RI#
DTR#
Label
5
4
11
17
18
12
Pin
CX84100-41/-23 SCXV.22bis Modem Data Sheet
I
O
O
O
O
I
I/O
V.24 (EIA/TIA-232-E) DTE Serial Interface
Itpu/Ot2
It/Ot2
Itpu/Ot2
It/Ot2
It/Ot2
Itpu/Ot2
I/O Type
Conexant
Transmit Serial Input (EIA BA/ITU-T CT103). Serial data is sent
on this line from the DTE to the DCE. The DTE holds this line at
logic 1 when no data is being transmitted. The following signals
must be at logic 0, where implemented, before data can be
transmitted on this line: Request To Send (RTS), Clear To Send
(CTS), and Data Terminal Ready (DTR).
Receive Serial Output (EIA BB/ITU-T CT104). Serial data is
sent on this line from the DCE to the DTE. This pin is held at logic
1 (Mark) when no data is being transmitted, and is held logic 1 for
a brief interval after a logic 0 to 1 transition on the Request To
Send line (RTS), in order to allow the transmission to complete.
Clear To Send (EIA CB/ITU-T CT106). An answer signal to the
DTE. When this signal is active, it tells the DTE that it can now
start transmitting. When CTS is logic 0 and the Request To Send
(RTS) and Data Terminal Ready (DTR) are both logic 0, the DTE
is assured that its data will be sent to the communications link.
Logic 1 indicates to the DTE that the DCE is not ready, and
therefore data should not be sent.
In asynchronous operation, in error correction or normal mode,
CTS is always at logic 0 unless RTS/CTS flow control is selected
by the &Kn command.
In synchronous operation, the modem also holds CTS at logic 0
during asynchronous command state. The modem switches CTS
to logic 1 immediately upon going off-hook and holds it there until
RLSD is at logic 0 in which case the modem is ready to transmit
and receive synchronous data. CTS can also track the state of
RTS via the &Rn command.
Received Line Signal Detector (EIA CF/ITU-T CT109). The
DCE uses this line to signal the DTE that a good signal is being
received assuming AT&C0 command is not in effect (a "good
signal" means a good analog carrier, that can ensure
demodulation of received data).
Ring Indicator (EIA CE/ITU-T CT125). On this line the DCE
signals the DTE that there is an incoming call. This signal is
maintained at logic 1 at all times except when the DCE receives a
ringing signal.
Data Terminal Ready (EIA CD/ITU-T CT108). When at logic 0,
DTR# tells the DCE that the DTE is available for receiving. The
DTR signal deals with the readiness of the equipment, as
opposed to the Clear To Send (CTS) and Request To Send
(RTS) signals that deal with the readiness of the communication
channel.
Logic 1 places the modem in the disconnect state under the
control of &Dn and &Qn commands.
Signal Name/Description
3-5