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3080/V24
124001UA
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ANUAL
In the Scanning Mode the 3080/V24 (CTS DSD-8) scans each Sub-Channel, in sequence,
beginning with Sub-Channel 1. This rotational sequence is repeated continually with each
attached Sub-Channel having equal access to the communications link. When data or control
lines from a Sub-Channel become active that Sub-Channel is switched through to the master
port by the 3080/V24 (CTS DSD-8). All remaining Sub-Channels are locked out until the first
device becomes inactive. When the Sub-Channel device becomes inactive, the 3080/V24
(CTS DSD-8) will resume scanning the Sub-Channels for another active signal.
When configured for Priority Mode operation, the 3080/V24 (CTS DSD-8) monitors all Sub-
Channels simultaneously with Sub-Channel 1 having the highest priority. When a Sub-Channel
becomes inactive, the 3080/V24 (CTS DSD-8) will automatically default to the highest priority
(lowest number) Sub-Channel with activity.
Contention for the Master port is accomplished by asserting RTS (Request to Send) if the
Sub-Port is configured as a DCE, DCD (Data Carrier Detect) if the Sub-Port is configured as
a DTE or Data Transitions from the attached Sub-Channel devices in either configuration. The
active interface lead RTS or DCD can be selected on an individual basis for each Sub-
channel, selection of contention mode,
“Data Transitions” or “Interface Lead” activation is
selected in Sub-channel groups. Sub-channels 1 thru 4 are the first group and Sub-channels 5
thru 8 are the second group. All Sub-channels in a group will be set to the same contention
mode, either
“Data Transitions” or “Interface Lead” activation. Once a Sub-Channel asserts
an active control signal, that control signal will be passed through to the Master Port,
depending on DTE / DCE configuration of the Sub-Channel and Master Port. This control will
be passed without delays. If the Master Port is configured as a DTE the signal will be passed
as RTS. The CTS returned to the Master will have an optional delay added before the signal is
returned to the Sub-Channel port.
Port Enable / Disable, front panel switches must be pushed in (GREEN indication) for a Sub-
Channel to access the Master Port regardless of the mode of operation selected.
Channel Tail Circuits
A buffer is built into the unit for tail circuit (DCE to DCE) applications. An 8 bit centered ring
buffer is used to correct the clock phasing errors generated between the Modem on the
Master Port and the Sub-Channel port for the data transferred from the Sub-Channel to the
Master Port. If the unit is operated in an asynchronous environment the buffer must be
bypassed. This is accomplished by moving the SYNC/ASYNC switch to ASYNC.