Telebit WorldBlazer User Manual page 54

Pin
22
23
24
25
Table 8-1. RS-232 Connector Pin Assignments
EIA CCITT
From To
Circuit Signal
Description
Modem Modem
CE
125
Ring Indicator (RI)
X
CH
111
OTE Signal Rate Selector
X
OA
113
OTE Transmit Signal Element
X
Timing
TM
142
Test Mode X
RS-232 Primary Interchange Signals
The modem hardware supports all data, control, and
timing signals defined by the RS-232 standard. However,
when operating in asynchronous mode, the modem uses
only the primary interchange circuits defined in Figure
B-1. This figure shows the cable configuration for
connecting the modem to a standard DTE device.
For systems that require the modem to act as a DTE
connected to a DCE device, a specially modified RS-232
cable must be used. Figure B-2 shows a recommended
cable arrangement for this case. Your system may require
a different cable configuration. Consult your equipment
manual for specific cabling requirements.
The primary interchange signals used by the modem in
asynchronous mode are described in the following
sections.
Protective and Signal Ground
90257-01
Pin 1 (protective ground) should be electrically connected
to the frame or chassis of the equipment. The equipment
may be further connected to an external earth ground as
required by local electrical codes. Pin 7 (signal ground) is
Interface Description 8-3