Telebit WorldBlazer User Manual page 58

Test Signals
Remote Digital Loopback
The local DTE uses pin 21 (remote digital loop back) to
place the modem into remote digital loopback. The
modem must be connected to a remote modem and must
be in the data mode. When pin 21 is turned on, the modem
requests that the remote modem loop back all data sent
from the local modem. When pin 21 is turned off, the
modem returns to the data mode.
Local Analog Loopback
The local DTE uses pin 18 (local analog loopback) to put
the modem into local analog loop back. Ensure that the
modem is offline and in the command mode. When pin 18
is turned on, the modem enters local analog loopback. All
data received on the primary transmit data pin (pin 2) is
modulated, demodulated, then looped back on the
primary receive data pin (pin 3). When pin 18 is turned
off, the modem returns to the offline condition.
Test Mode
Pin 25 (test mode) is a signal from the modem to the local
DTE signifying that the modem is in a test mode. The test
mode may be initiated either through the &T commands
or the remote digital or local analog loopback RS-232
pms.
Rate Select Signals
DTE Signal Rate Select
90257-01
The local DTE uses pin 23 (DTE signal rate select) to
select between a primary signaling rate and the fallback
rate. The only modulation modes that use pin 23 are
Interface Description 8-7