Specifications

X723-300151 1-10 Issue 2
Cross-connection modes supported are:
Simplex: for uni-directional and broadcast data.
Duplex: for bi-directional data.
Multipoint: for point to multipoint services.
To 'undo' a cross-connection it is necessary to allocate fixed data to the
outgoing timeslot. If the connection was in duplex it is necessary to
individually allocate fixed data to each outgoing timeslot, this is because a
duplex connection, for example P3, TS 1 to P4, TS2 sets up 2 simplex
connections for the two outgoing timeslots, P3 TS1 to P4, TS2 and P4 TS2
to P3 TS1.
Multipoint allows timeslots from Port 3 (P3) to be 'AND'ed together with
incoming data from any backplane stream, the result is then inserted into
the outgoing backplane stream. This allows timeslots, hence circuits that
support Multipointing, to be cascaded together such that all of them can
insert and drop data from one timeslot. The end of the chain is referred to
as the master and is connected to many slave cards. The master usually
broadcasts data to all slaves. For correct operation, only one slave may be
active i.e. inserting data at a time. While inactive, the slave should insert
'all ones' towards the ‘AND’ gate, thereby allowing data from the active
slave to pass through.
Currently, multipoint cards exist for X.21, Dual V.24 and 2/4 wire voice
circuits. For multipointing to operate a channel card must
NOT be fitted in
port 1; it may be fitted with a Dual LIU or left empty.
Programmable fixed codes are not available for multipoint mode. In these
cases an 'all ones' data pattern will be generated under fault conditions in
each timeslot affected.