User`s guide

Characteristics of a Well-Designed System
Well understood strategies used with the SLTA-10 Adapter and the SLTALink
Manager for the following system functions are essential for reliable system design:
Call Initiation, Call Termination, and Monitoring.
Call lnitia tion
The four scenarios for call initiation are: dial-in to the network only, dial-out to the
remote PC only, dial-in / dial-out, and callback.
Dial-In to the Network Only
In the most straight-forward case, a user launches an application. The application
opens the driver, which is associated with a particular link. The SLTALink Manager
application dials the phone number in the link (or the phone number the application
passes down to the SLTALink Manager perhaps to a generic link) and establishes the
connection. Similarly, the user could select the link from within the SLTALink
Manager and cause a manual connection. At this point, either the SLTALink
Manager would launch the pre-determined application from the information stored in
the link file or the user could manually launch the application. In all of these cases,
the user is assumed to initiate the call. The user could be a human operator or
another application that initiates a dial-in based on a clock, for example.
For the dial-in only scenario, the system strategy issues primarily have to do with
associating the link or phone number with the application. Where there are only one
or two links, this is very easy. When one PC host can be connected to many different
networks, we offer two standard solutions. The first is to have the user navigate the
SLTALink Manager’s GUI. Under the Link menu, the Select item lists
approximately 40 links (of the 1000 possible). The second solution is a monitoring
application that programmatically interacts with the SLTALink Manager to send
down the appropriate phone number, perhaps to a generic out-going link.
Dial-Out to the Remote PC Only
The three common approaches for initiating a dial-out are: sending a network
variable update to the SLTA-10 Adapter, sending an AddMyNSI message to the
SLTA-10 Adapter, or sending an explicit message from a “Helper/Dialer” node on the
network.
In the first case, the remote host application needs to have an explicitly-bound input
network variable and the SLTA-10 Adapter’s NSI mode EEPROM must be configured
correctly. See the configuration section in this chapter or go to Chapter 11 for more
information on configuring the SLTA-10’s EEPROM. See also Call Termination
below.
In the second case, the remote host PC is assumed to have the NSS engine and a
second NSI on the network (perhaps a service technician with a laptop running a
PCC-10 card) is required to send the AddMyNSI message. Also, SLTA-10 Adapter’s
NSI mode EEPROM must be configured correctly.
SLTA-10 Adapter User’s Guide
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