East Coast Datacom Nx8- Dual Composite MUX High-Speed 16-Port TDM..., Operation Manual

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For the Nx8-DualMUX, any parameter entry to the composite link rate causes the system to
1) resize the timeslot allocation memory map to the new frame size, 2) re-allocate all
channels with non-zero clock rates to fit in the new allocation map, and 3) stores the
complete configuration in non-volatile memory. Channels that have been previously de-
allocated, but have a rate assigned to them other than zero, will be re-allocated at the rate
assigned, beginning with channel 1 and proceeding in an ascending order up to channel 16.
Should there be insufficient composite bandwidth at the new rate to accommodate all
channels at their assigned rates, the system will de-allocate those channels by number
higher than last channel allocated, but will leave their assigned rate unchanged. Thus for
example, if channels 1 through 12 fit into the new capacity of the composite link at their
assigned rates, but channel 13 will not, then channels 13 through 16 will be de-allocated and
their assigned rate will remain unchanged. If at a later time, the composite link rate is
increased and one or more of channels 13 through 16 can be accommodated, they will be
allocated bandwidth at their previously-assigned rate.
As a result of the above channel re-allocation, all channels will potentially be disrupted and
cannot be returned to service until both local and remote systems have been given equivalent
commands to modify the composite link rate. Even then, unless the channel bandwidth
parameters in both systems are identical, channel timeslots will not match. In such cases, the
operator should use the “Copy Mixed Configuration to Remote” command (see section
2.2.6.3 ).
2.1.6.5 Control Signal Leads
The state of the RTS lead on the composite port may be selected by configuration option.
The DTR lead is set ON when electrical power is applied to the system.
2.1.6.6 Composite Port Loop Options
The Composite Port may be put into one of two loop configurations by user command. These
two loop modes are termed Receive loopback and Transmit Loopback and are mutually
exclusive.
The diagram of Figure 6 illustrates both modes. In receive loopback (left), the same data that
is received at the composite port is also sent to the transmit side of the interface in place of
the data that is normally sent on the TxD lead.
In transmit loopback (right), the same data that is transmitted at the composite port is also
returned to the receive side of the interface in place of the data that is normally received on
the RxD lead.
RXD
TXD
RXD
TXD
Composite
Port
Receive Loopback
RXD
TXD
RXD
TXD
Composite
Port
Nx8-MUX
Transmit Loopback
Nx8-MUX
Figure 6 – Composite Port Receive and Transmit Loopback Modes