USRobotics V.34 - Manual (Page 167)

COURIER HIGH SPEED MODEMS
F-2 Synchronous Operations
NOTE: The term DTE in the following discussion means Data
Terminal Equipment, the end-to-end equipment involved in
data communications. DTE denotes your terminal or computer
and the remote computer.
What You Need to Know
The network's communications management staff can supply
information on the following requirements:
• The protocol needed for your calls
• The software support needed to log into the network;
for example, a specific communications package or
interface board
• The phone number, if you will be calling instead of
answering
• Any restrictions about when you can call
The RS-232 Interface
Transmit and Receive synchronous timing pins are required at
the RS-232 interface. You'll need either pin 15 or pin 24 for
Transmitter timing signals, depending on whether the modem
(pin 15) or the DTE (pin 24) generates the signals. You'll also
need pin 17, for Receiver timing signals. If you're building your
own cable, review the
RS-232 Interface, in Appendix B.
Protocol Compatibility
The devices at both ends of the link must use the same protocol.
These protocols format data into blocks or frames and add
control information.
If the modem is in V.25 bis mode, the link protocol must be
HDLC (High-Level Data Link Control), or character-oriented. If
the modem is in Online Synchronous mode it may use HDLC,
character-oriented, or another protocol determined by the
mainframe manufacturer.