Technical data

Managing Peripheral Devices
8.7 Managing Modems
Figure 8–2 depicts direct and indirect modem configurations. The remote devices
T1 and T2 are indirectly connected to both Host1 and Host2 host computers using
the DECserver and the LAT protocol; T3 is connected directly to Host2.
Figure 8–2 Direct and Indirect Modem Configurations
Terminal 1
Modem Modem
Digital
signal
Phone line
Terminal 2
Terminal 3
Modem
Modem
Modem
Hardwired
Digital
Digital
signal
signal
Phone line
Phone line
DECserver
Host 1
Host 2
LAT or Telnet
over Ethernet
Ethernet
Ethernet
ZK−9058A−GE
Once you decide which serial communications port to use, either on a host or a
terminal server, you need to determine the connectors and the pinouts for the
port and how to wire the modem to the port. Refer to the documentation for the
modem and for the port; also see Section 8.7.2.
8.7.2 Setting Up Modems
Follow these steps to set up modems:
1. Determine connections and wiring pinouts.
The connector and pinout determine the specific wiring adapters and cables
you need to connect the modem to the port. To determine the pinout and the
connector on the modem, and the pinout and connector on the port you are
connecting the modem to, refer to the modem and the port documentation.
Two common pinouts found on the EIA-232 DB25 connection are shown in
Table 8–4.
Managing Peripheral Devices 8–27