| The RSD-10 Digital Sharing Device
enables up to 8 modems or terminals to share a master modem, a
multiplexer or a computer port in a multipoint environment. It
operates at seven selectable data rates up to 19.2 kbps, synchronously
or asynchronously.
Three clock modes are supported:
1) Internal
2) External from the main channel
3) External from DCE connected to sub-channel 1.
A built-in buffer overcomes clock differences between the modem clocks
connected to the sub-channels and the RSD-10 main channel transmit
clock.
An additional buffer can be switch-selected for
equipment which must provide clock to multiple sub-channels.
(Examples are D.D.S. in the U.S., any digital service in other
countries, or modems that cannot be set to an external clock.)
Information is broadcasted by the main channel
to all sub-channels in parallel. Sub-channels contend to transmit to
the main channel by activating RTS/DCD, or by data transition
(strap-selectable). If the RTS/DCD or data of a sub-channel is active,
the sub-channel's transmit data and control signals are connected to
the main channel. When RTS/DCD drops or data transmission ceases, the
control circuitry switches to monitor other sub-channels.
A sub-channel is disconnected immediately after
it drops RTS/DCD or transmits 16 idle bits.
To prevent blockage to other sub-channels in
event of streaming, a sub-channel can be disabled by automatic
circuitry if it remains active for longer than a preset time.
The automatic disable resets whenever the sub-channel RTS/DCD drops,
or 16 idle bits are transmitted (data contention). Front panel
indication is provided for each sub-channel disabled by automatic
circuitry. The sub-channel can be manually disabled from the front
panel as an alternative.
Installation and configuration of the RSD-10 is
simple. Minimal strapping adjustments enable easy installation and
operation. All necessary crossover connections are performed
internally, and only straight-through cables are used to connect the
modems or terminals to the RSD-10. The RSD-10 is provided with special
hardware for mounting in a 19" rack, occupying 1U in height. |
