Optelecom 9525A, Инструкция по установке и эксплуатации

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2.1.3 Fault Tolerant Redundant Ring With the architecture shown in Figure 3, all modems are arranged along
a dual fiber ring starting with the master controller modem (operating in Master Fault Tolerant mode),
looping through a number of local terminal modems (operating in Local Fault Tolerant mode), and
terminating back into the second set of optical ports of the master controller modem, completing the
ring.
In this architecture the master modem transmits data in both directions around the ring and receives
its own signal. The ring is terminated at the master modem. In other words, the data is not repeated
by the master modem, but instead it ends there.
Each local modem in the ring transmits its input data in both directions, receives from both directions,
and retransmits in both directions the data received by the optical receivers. Each local modem,
receiving data from the master from both directions around the ring, will select the data that arrives
first and output that signal to the data port. If the transmission is interrupted in that direction, the
modem will automatically select the data from the other direction. The master modem also receives
data from both directions from each of the local modems, and selects the first arriving data in the
same manner.
In this mode, the master will normally receive an echo of its own signal. To disable the echo, select the
ECHO OFF on the Mode switch bank. Enabling the “ECHO OFF” is imperative for RS485 2-wire
operation.
2.2 Modes of Operation
To set up a modem into one of its four operating modes, the user selects one of four combinations for
switch sections 1 and 2 of the MODES dipswitch.
These four modes are characterized by the specific signal routing within the modem, shown in Figure 4.
The following sections include a detailed description of each mode described in Figure 4.
2.2.1 Master Daisy Chain Mode
In this mode a TD input to the data port is transmitted out via the TX1 and TX2 optical ports and out
the expansion port as RDE in RS232 format. With the
INDICATORS mode switch in the up position, a TD input will cause the TX1, TX2 and RDE indicators to
illuminate.
Conversely, an optical input via the RX1 or RX2 optical port or an RS232 input via the expansion port will
be output via the DB25 port as RD.