2.4
RS-232 ELECTRICAL INTERFACE
The DMM-4DC user data ports are EIA RS-232 compliant, utilizing female DB-25 connectors.
Refer to the interface chart in the Appendix for detailed interface information. The maximum
data rate is 128kbps. The unit incorporates surge protection on each RS-232 data port.
2.5
SUBCHANNEL SERVICE MODES
The DMM-4DC incorporates circuitry that enables the user to scan each sub-channel port.
2.5.1
SUBCHANNEL SCANNING
Subchannel
Scanning
will allow equal access to the communications link for all connected DCE
or DTE devices. The subchannels are
scanned
in sequence (1 - 2 - 3 - 4) and the attached
subchannel DCE that raises DCD or DTE that raises RTS will have access to the
communications link. After dropping RTS the DMM-4DC will continue
scanning
in sequential
order.
2.5.2
SUBCHANNEL RTS TO CTS DELAY
RTS to CTS delays
of 0, 5, 10 and 20ms are user selectable.
2.6
ANTI-STREAMING
2.6.1
AUTOMATIC DTE REMOVAL
The DMM-4DC incorporates circuitry that will (when enabled)
automatically
remove a
streaming DCE or DTE from service. A streaming terminal is defined as a terminal that has RTS
high
longer than the user predefined anti-stream timer has been set. Upon installation, the user
can set or actually fine tune the timer to your network requirements. Each channel has a Green
and a Yellow LED to indicate subchannel activity. Green indicates an active subchannel and
Yellow indicates a streaming subchannel. Once a terminal has gone into the streaming condition
(RTS continually high) the DTE will automatically be removed from service until the DTE fault
has been corrected by the user. All other DTE's will continue to be serviced.
2.7
SYNC AND ASYNC SELECTION
The DMM-4DC incorporates circuitry that allows the user to select
Synchronous
or
Asynchronous
operation.
DMM-4DC OPERATIONS MANUAL
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