Msg: 4555 *Conference*

07-25-93 22:05:04

From: DREW BLANCHAR

To : CARROLL LEWIS

Subj: REPLY TO MSG #4537 (BASIC STUFF)

 >    1.Is the null modem REQUIRED for the RS-232 cable when 
 > connecting two model T's? (I have it, so I blindly 
 > followed directions)

Yes.  Each computer is considered a DTE (data terminal equiptment) which means
(by the RS-323) it transmits its signal on pin 2 and receives a signal on pin
3.  So you have to cross or null out the cable.   
 >  
 >    2.Can the computers be set to terminal mode if the 
 > phone lines where first used for voice tranmission? (In 
 > other words if my sales girl calls me to say that she has  
 > her sales file ready can I tell her what to do and simlpy 
 > enter terminal modes and transmit or must we hang up and 
 > let the computers establish the call?)

Yes.  The telco line come from the wall, into the computer to a relay.  When
the machine (or any good modem for that matter) is OFF, the relay connects the
telco line to the output jack to the phone set. As soom as you activate the
modem, the relay switches internal electronics onto the circuit to the "wall".
This way you can dial by hand, listen for the far modem tone, then switch your
modem on line.
  
Have fun.
-dB