RSD-10 8 channel Digital Sharing Device
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. The RAD RSD-10 operates at seven selectable data rates up to 19.2 kbps, synchronously or asynchronously.
Three clock modes are supported on the RAD RSD-10:
2) External from the main channel
3) External from DCE connected to sub-channel 1.
The built-in buffer of the RSD-10 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 of the RSD-10 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-channelís 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.
RSD-10 operates in one of six modes: modem sharing, port sharing, remote port
sharing, local port sharing, mix modem sharing and mix port sharing.
RSD-10 product data sheet (pdf)