Black Box Figure 2-8. Dialup Connection.

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CHAPTER 2: Introduction
PC or through up to 64 auxiliary communication ports mounted on intelligent
serial multi-port units.
The connections between the PC and the rack can be of two types:
1.Dedicated line between the PC and a site. The site is always online with the PC
(hardwired).
2.Dialup modem connection between the PC and a site (see Figure 2-8). The
connection is established when needed.
You can program communication ports from the PC to be either dedicated
ports or dialup modem ports.
Figure 2-8. Dialup Connection.
2.4.2 D IALOGWITH D IALUP S ITES
Normally, all dialup sites are off-line. You initiate the dialing of the site’s telephone
number when you execute a command that requires communications with a rack
on a dialup site. When the connection is established, the remote site comes online
and polling starts.
From the moment you make the connection, you can send commands to the
racks on that site and receive status data from the racks.