Boundless adds 4000 用户指南

12     Introduction

 

Terminal to Modem (DCE) or Host 
Refer to the diagram below to understand why a null modem adapter may be needed 
when connecting the second serial port (SES2-AUX) to a modem or a DCE host.  The 
first host will connect directly without a null modem since it is a DTE device.  

 

 

Terminal to Host (DTE) or Printer 
Refer to the diagram below to understand why a null modem adapter may be needed 
when connecting the first serial port (SES1-EIA) to a host port without a modem 
(most serial printers are DTE devices and most hosts are not).  The second port (AUX) 
will connect directly, without a null modem, since it is a DCE device.