Pin |
Mnemonic |
Signal Name |
Description |
---|---|---|---|
1 |
|
Not Connected |
None. |
2 |
TXD |
Transmit Data |
Used by the data terminal equipment (DTE) to transmit data to the data circuit equipment (DCE). Except when control data is being sent, RTS, CTS, and DCD must be ON for this line to be active. |
3 |
RXD |
Recive Data |
Used by the DCE in response to received data from the DTE. |
4 |
RTS |
Ready to Send |
Used by the DTE to condition the DCE for data transmission. The transition to ON directs the DCE to go into transmit mode. The transition to OFF directs the DCE to complete the transmission. |
5 |
CTS |
Clear to send |
Used by the DCE to indicate if it is ready to receive data from the DTE. When CTS, DSR, RTS and DTR are ON, the DCE is ready to transmit data received from the DTE across the communications channel. When only CTS is ON, the DCE is ready to accept dialing or control signals only. When CTS is OFF, the DTE should not transfer data across TXD. |
6 |
DSR |
Data Set Ready |
Used by the DCE to indicate if it is ready to operate. When DSR is ON, the DCE is connected to the line and ready to exchange further control signals to start data transfer. |
7 |
Gnd |
Signal Ground |
|
8 |
DCD |
Data Carrier Detect |
Used by the DCE to indicate it is receiving a suitable signal from the communications channel. |
9 |
|
Not connected |
None. |
10 |
|
Not connected |
None. |
11 |
|
Not connected |
None. |
12 |
|
Not connected |
None. |
13 |
|
Not connected |
None. |
14 |
|
Not connected |
None. |
15 |
TRXC |
Transmit Clock |
Used by the DCE to provide timing information to the DTE. The DTE provides data on TXD in which the transition of the bit corresponds to the rising edge of the clock. |
16 |
|
Not Connected |
None. |
17 |
RTXC |
Receive Clock |
Used by the DCE to provide timing information to the DTE. The falling edge of the clock corresponds to the center of the data bit received on RXD. |
18 |
|
Not connected |
None. |
19 |
|
Not connected |
None. |
20 |
DTR |
Data Terminal Ready |
Used to control switching of the DCE to the communication channel. |
21 |
|
Not connected |
None. |
22 |
|
Not connected |
None. |
23 |
|
Not connected |
None |
24 |
TXC |
Terminal Clock |
Generated by the DTE to provide timing information to the DCE. Used only in synchronous mode and only when the driver requests a locally generated clock. Otherwise, TXC echoes the modem-generated clock. The falling edge of the clock corresponds to the center of the data bit transmitted on TXD. |
25 |
|
Not connected |
None. |