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2. Set input impedance of both modems to 200. (S3-1 “On”, S3-2
“Off”)
3. Set data rate on both modems 9.6kbps. (S1-1 “On”, S1-2 “Off”, S1-
3 “Off”, S1-4 “On”)
4. On local modem set “Carrier Constantly On”. (S1-8 “Off”)
5. Set remote modem to RTS control (S1-8, “On”).
6. Place both front panel toggle switches to neutral position. (Test Led
will not light)
7. Connect both modems to the 4 wire twisted pair cable to be tested.
(see “Twisted Pair Connection” on page 23)
Reading The Test
A. If line quality is good, “Error” LED on local modem will not light and
“CD” LED will be red. On remote modem “Error” LED will not light and
“CD” LED will light green.
B. 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.
C. 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.
5.2 ANTISTREAMING 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 Model 1080A’s anti-
streaming circuitry is enabled, the RTS signal from the DTE is timer con-
trolled. The timer begins to count when the DTE raises RTS. If the time
period that RTS remains high exceeds the preset timeout period, the
antistream circuit will force RTS low. The “Error” LED will light red, indi-
cating a streaming condition (RTS continually on). This feature prevents
a malfunctioning terminal from tying-up a computer port in a multidrop or
polling environment. When the DTE drops RTS, the antistreaming 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.