Black Box ME475A-R2, Manual

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Operation
2. If flat cable is used or parts of the line are flat cable, “Error” LED on local modem
will light red and “CD” LED will light green. On remote modem “Error” LED will
not light and “CD” LED will light green.
3. If one wire from the 4 wire twisted pair is broken “Error” LED will light red and
“CD” LED will light green on at least one modem.
Note We cannot guarantee accurate detection if small pieces of flat cable are present
in the line beyond 1500ft of the local modem.
4.2 ANTI-STREAMING ERROR INDICATOR
When not in test mode (green “Test” LED is off), the front panel “Error” LED is used to
indicate a streaming error. When the ME475A-R2’s anti-streaming circuitry is enabled,
the RTS signal from the DTE is timer controlled. The timer begins to count when the DTE
raises RTS. If the time period that RTS remains high exceeds the preset time out period,
the anti-stream circuit will force RTS low. The “Error” LED will light red, indicating a
streaming condition (RTS continually on). This feature prevents a malfunctioning termi-
nal from tying-up a computer port in a multi-drop or polling environment. When the DTE
drops RTS, the anti-streaming timer is automatically reset and the front panel “Error”
LED turns off. The time out period is DIP switch selectable for 12.5 or 50 seconds.
4.3 POWER-UP
Apply AC power to the ME475A-R2 by plugging the separate AC power adapter first
into the rear panel of the ME475A-R2, and then into an acceptable AC power outlet.
There is no power switch on the ME475A-R2; and the remote/normal/loopback switch
should be set to “normal”. When the local and remote ME475A-R2s are both powered
up, and passing data normally, the following LED conditions will exist:
• TD & RD = flashing red and green
• RTS & DCD = green
• TEST = off
4.4 V.54 TEST MODES
The ME475A-R2 offers two V.54 test modes to evaluate the condition of the modems
and the communication link. These tests can be activated physically from the front
panel, or via the RS-232 interface
Note V.54 test modes are available for point-to-point applications only.