Installation; System Architecture - Optelecom 9525AY/SM-FC Installation And Operation Manual

2 - INSTALLATION

2.1 System Architecture

The Model 9525AY can be configured into three basic network architectures with almost unlimited
variations. Typically the rack mountable Model 9521Y is used at the central hub. The standalone
Model 9525AYs are used at the remote (local) locations. However, either modem can be used in either
installation if so desired.
To use the modems to serve various functions in the network they may be configured into one of four
operating modes, characterized mainly by the internal signal routing within the modem among the
electrical RS232 and expansion ports and the two optical transmitter/receiver ports.
In addition to the routing of the data signals within the modem that characterizes its mode of
operation, there are several other operational features that are important to know. Some of these
features are inherent, some are optional, and others are absent depending on the mode of operation.
In the following sections 2.1, 2.2, and 2.3 these operational features, the four modes of operation, and
the three basic network architectures and their variations are discussed in detail.
The Model 9525AY can be configured into three basic architecture types with almost unlimited
variations. They are:
a) Daisy Chain with one master controller
b) Daisy Chain with two master controllers
c) Fault Tolerant Counter Rotating Ring
The following sections describe these in detail.
2.1.1 Daisy Chain Mode with One Master Controller (Refer to Figure 2)
With this architecture, one master controller lies at the end of one or more main trunks, if you define a
main trunk as a daisy chain that roots at the master controller. In all cases, a Model 9525AY set in
Master Daisy Chain Mode will be used as the master modem. A number of 9525AYs can be connected
together to form multiple trunks by running a cable from the expansion port of the first modem to the
RS232 port of the next and so on. The section on wiring the expansion port (2.7.3) gives a schematic
diagram of the cable used in connecting the expansion port to the next modem.
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