2..10 CASCADING OR CONCATENATION
The DMM-X21 supports cascading by utilizing DB-15 Male-to-Male straight through
shielded cables.
Subchannel Port 1
should be used as the concatenation port.
2.8 MANUAL DTE/DCE REMOVAL
The DMM-X21 incorporates circuitry that will (when enabled)
manually
remove a
streaming terminal from service. A streaming terminal is defined as a terminal that has
Control (C) continually
high
. With Anti-streaming disabled, the associated streaming
DTE will
NOT
illuminate a Yellow LED on the front of the DMM-X21. If the automatic
anti-streaming circuitry is disabled and a streaming condition occurs, the other DTE
devices will be blocked from accessing the communications link. To correct this
condition, simply push the associated
push-button switch
for the subchannel that is
streaming. All other DTE's will now continue to be serviced by the DMM-X21.
However, you still need to fix the offending DTE or DCE device that has Control (C) or
Indicate (I) continually raised.
2.9 FALL BACK TIMING
The DMM-X21 incorporates circuitry that allows the user to provide
Fall Back Timing
to
the network. The circuity allows the user to enable or disable this funtion via Dip
Switch. To enable fall back Timing, go to the dip switch marked S11 and move position
8 to ON. This will provide Port 1 as the main timing source. If Port 1 clock fails, the unit
will automatically switch to Port 2 as the timing source. If Port 2 fails, the unit will
automatically fall back to internal clock as the timing source. If Port 1 clock returns to
service, the unit will automatically switch back to Port 1 timing.
East Coast Datacom, Inc. DMM-X21 OPERATIONS MANUAL
Page 5
D
M
M
D
M
M
MODEM
CONNECT TO MASTER PORT
CONNECT TO PORT 1
DB-15 CABLE
CASCADING DIAGRAM
OR F.E.P.
