Справочник Пользователя для B&B Electronics 485DSS

485DSS-0308 Manual 

 

3 

B&B Electronics  – Westlink Commercial  Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445

 

The RS-232 DTE port is an asynchronous port that supports TD 

and RD signals.  In order to make the proper connections to the RS-
232 port. It is necessary to have a basic understanding of the terms 
DCE and DTE.  The original design for connecting RS-232 devices 
together uses DB25 connectors, and connects a DTE (Data 
Terminal Equipment) device to a DCE (Data Communication 
Equipment) device.  Each device will have inputs on pins that 
correspond to outputs on the same pins of the other device.  For 
example, a DTE device transmits data out on pin 2 and a DCE 
device receives data in on pin 2.  IBM PC's are DTE devices and 
modems are DCE devices.  Only TD and RD of the RS-232 port 
pass through to the RS-485 port when the 485DSS is ON.  The 
485DSS raises and lowers the RTS output signal on the RS-232 
port to reflect the connect state of the port.  This signal can notify the 
RS-232 device to start communicating to the Host or it can be an 
alarm output.  The Host can monitor the CTS input line to determine 
if the RS-232 device is requesting access to the network.  This input 
line could also be an alarm input.  NOTE:  If using RTS or CTS lines 
as alarms the user may have to design additional circuitry to 
properly interface to the alarm circuits.  Refer to cable charts in 
Appendix C for making your own cables. 

FR GND  Frame Ground 

<------> 

TD(A)(-)  Transmit Data (A)(-) 

Output 

 TD(B)(+)  Transmit Data (B)(+)  Output 

 RD(A)(-)  Receive Data (A)(-) 

Input 

 RD(B)(+)  Receive Data (B)(+) 

Input 

 GND 

Signal Ground 

<------> 

+12VDC Power 

Supply 

Input