Telex Azedit, Software Manual

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Telex Communications 109
XPT (Crosspoint)
When one intercom port talks to another intercom port it does this via what is commonly referred to as a crosspoint.
The crosspoint is basically the connecting point between the talker and the listener. There is a separate talk and
listen crosspoint between every intercom port and every other intercom port in the intercom system. The term
Crosspoint, like the term Matrix, is inherited from intercom systems, such as the RTS™ CS9500, CS9600, and
CS9700, which use a switching matrix to route the intercom audio. In those systems, the crosspoint are actual
switches that close or open to connect or disconnect talk and listen paths. RTS™ ADAM, ADAM CS, and Zeus
intercom systems do not actually use crosspoint switches, but a technology called time division multiplexing
(TDM), in which communications are routed as digital packets.
Methods of Crosspoint Activation
Keypanel Key Assignments: Crosspoints turn ON and OFF as keypanel operators press keys to talk and listen to
each other. You assign keys using keypanel setup.
Forced Crosspoint: You can force a specific intercom port to always talk or listen to another intercom port. You can
force crosspoints in the Crosspoint Status screen.
Party Lines: When an intercom port is assigned to talk and/or listen to a party line, the talk and/or listen crosspoints
are permanently closed between that intercom port and all other intercom ports that are members of the party line.
Removing a member from a party line will release the crosspoints. Members are assigned to party lines using party
line setup.
Talk vs. Listen
In terms of crosspoints, talking from one port to a second port is the same thing as the second port listening to the
first port. However, this does not mean that any intercom port can arbitrarily listen to another intercom port. For
example, lets say a keypanel operator at intercom port 1 presses a talk key to talk to a keypanel operator at intercom
port 2. This causes 2 things to happen. First, pressing the key causes a data message to be sent to the intercom
system, which tells the intercom system to turn on the crosspoint that connects intercom port 1 to intercom port 2.
Second, pressing the key activates the microphone amplifier in the keypanel at intercom port 1. This allows the
person at intercom port 2 to hear the person at intercom port 1. Note that the person at intercom port 2 could activate
the same crosspoint by activating a listen key. However, since this does not turn on the microphone in the keypanel
at intercom port 1, nothing can be heard (unless the microphone is already on to talk to some other destination).