Optelecom 9525A, Инструкция по установке и эксплуатации

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1 - INTRODUCTION
1.1 General description
The TKH Security USA Model 9525A is an RS232, RS422, and RS485 compatible stand alone fiber optic
modem with dual optics for drop and insert applications which can be configured in a wide range of
poll/response network architectures. The unit operates using two optical fibers to transmit and receive in the
upstream direction. A second pair of fibers is used in the downstream direction. This results in the formation
of a two-fiber daisy chain or ring.
The units may be operated in either daisy chain or fault tolerant redundant ring architectures. In addition, in
certain modes, an RS232 expansion port on the modem may be connected to a second modem with single or
dual optics to branch the network in one or two additional directions. With this capability a daisy chain
network may be set up with unlimited branches off the main trunk(s). Additionally, unlimited daisy chain
connections may be made branching off of a main fault tolerant dual fiber ring. All signals received via an
optical port and retransmitted via fiber or via the expansion port are re-timed to .01% pulse width accuracy by
a crystal controlled time-base, eliminating pulse width distortion and allowing virtually unlimited repeating.
The units have four switch selectable modes of operation: Daisy Chain Master mode, Daisy Chain Local mode,
Fault Tolerant Master mode, and Fault Tolerant Local mode. See Section 2, Installation, for a complete
description of these modes of operation.
The units may be operated in either daisy chain or fault tolerant redundant ring architectures. In addition, in
daisy chain mode an RS232 expansion port on the modem may be connected to another modem with single or
dual optics to branch the network in one or two additional directions. With this capability a daisy chain
network may be set up with unlimited branches off the main trunk(s).
The units have anti-streaming (sometimes referred to as anti-babbling) circuitry for both the optical fiber and
electrical (RS232) sides. On the RS232 side, when enabled, the anti-streaming limits the amount of time a
terminal is allowed to transmit data onto the network for each Request to Send. This is to prevent a faulty
terminal unit from monopolizing the network. On the fiber side the anti-streaming disables an optical receiver
in the event that the receiver output stays high longer than the maximum allowable time. This will prevent the
whole fiber network from being disabled by a continuous "on" failure by receiver or optical emitter. This
feature is not available when in RS422 or RS485 mode because the RTS line is not supported.
The units have nine front panel LED indicators. A POWER indicator is on solid when operating under primary
power and blinks if operating on an external gel cell battery in the case of the loss of the primary power
source. If operating in local mode, a FAULT indicator illuminates in the event of an RS232 anti-streaming
timeout. If operating in Master fault tolerant mode, the FAULT indicator illuminates if one of the two
redundant rings is broken. A relay with N.O. and N.C. contacts activates in conjunction with an illuminated
FAULT LED. A BERT indicator operates when properly receiving the BERT signal. The other six indicators serve
dual functions as selected by the indicator mode switch. In one position the LEDs indicate electrical side signal
activity. In the other position the LEDs indicate fiber port activity as well as the active fiber input port as
chosen by the priority select circuitry.
A ten-position MODES dipswitch allows the user to select the operating mode, Tx1 and Tx2 BERT Signal
Enable, and the data interface. In addition, an eight-position TIMEOUT dipswitch allows the user to select
timeouts for (or disable) the electrical side anti-streaming, the fiber activity CTS inhibit (RS232 mode), echo
cancel timeouts, and priority select timeouts.