Sony ECM-3711 Benutzerhandbuch

34 ECM-3711 Series User’s Manual 
 

 

TxD 

Serial output. This signal sends serial data to the communication link. The signal is 
set to a marking state on hardware reset when the transmitter is empty or when 
loop mode operation is initiated. 

RxD 

Serial input. This signal receives serial data from the communication link. 

DTR 

Data Terminal Ready. This signal indicates to the modem or data set that the 
on-board UART is ready to establish a communication link. 

DSR 

Data Set Ready. This signal indicates that the modem or data set is ready to 
establish a communication link. 

RTS 

Request To Send. This signal indicates to the modem or data set that the on-board 
UART is ready to exchange data. 

CTS 

Clear To Send. This signal indicates that the modem or data set is ready to 
exchange data. 

DCD 

Data Carrier Detect. This signal indicates that the modem or data set has detected 
the data carrier. 

RI 

Ring Indicator. This signal indicates that the modem has received a telephone 
ringing signal. 

TxD+/- 

Serial output. This differential signal pair sends serial data to the communication 
link. Data is transferred from Serial Port 2 Transmit Buffer Register to the 
communication link, if the RTS register of the Serial Port 2 is set to LOW. 

RxD+/- 

Serial input. This differential signal pair receives serial data from the 
communication link. Received data is available in Serial Port 2 Receiver Buffer 
Register. 

DATA+/- 

This differential signal pair sends and receives serial data to the communication 
link.  The mode of this differential signal pair is controlled through the RTS 
register of Serial Port 2. Set the RTS register of the Serial Port 2 to LOW for 
transmitting, HIGH for receiving. 

 

Do not select a mode different from the one used by the connected peripheral, 
as this may damage CPU board and/or peripheral. 
The transmitter drivers in the port are short circuit protected by a thermal 
protection circuit. The circuit disables the drivers when the die temperature 
reaches 150 

°C. 

RS-422 mode is typically used in point to point communication. Data and 
control signal pairs should be terminated in the receiver end with a resistor 
matching the cable impedance (typical 100-120 

Ω). The resistors could be 

placed in the connector housing. 
RS-485 mode is typically used in multi drop applications, where more than 2 
units are communicating. The data and control signal pairs should be 
terminated in each end of the communication line with a resistor matching the 
cable impedance (typical 100-120 

Ω). Stubs to substations should be 

avoided.