Using modems 10, Null modem cable and signals, Using modems – Lucent Technologies PortMaster User Manual
Page 159: Null modem cable and signals -1
10-1
Using Modems
10
This chapter explains how to configure external modems to work with PortMaster
products. For information on using the internal digital modems with the PortMaster 3,
see Chapter 11, “Configuring the PortMaster 3.”
This chapter discusses the following topics:
•
“Null Modem Cable and Signals” on page 10-1
•
“Modem Functions” on page 10-2
•
“Using Automatic Modem Configuration” on page 10-2
•
“Configuring Ports for Modem Use” on page 10-7
See the PortMaster Command Line Reference for more detailed command descriptions and
instructions.
Because the PortMaster is a DTE device, a straight-through RS-232 cable is used to
connect modems to it. Straight-through cables for modems use pins 2, 3, 4, 5, 6, 7, 8,
and 20.
Null Modem Cable and Signals
Ports S0 through S29 are asynchronous DTE ports with female RS-232 connectors. To
connect these ports to a terminal or other DTE, use a null modem cable, typically male-
to-female. Directions (input/output) are with respect to the PortMaster. The PortMaster
does not use the Data Set Ready (DSR) signal.
Note – When the console port is connected to a terminal, it uses software flow control
and therefore requires pins 2, 3, and 7 only.
Null modem cables can be obtained from most suppliers of computer equipment.
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