Black Box ME475A-R2, Manual

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Black Box Short Range Modem
The “Error” Indicators
The “Error” indicator LED has three functions:
1. When the ME475A-R2 unit is in test mode (green “Test” LED is lit), the error LED
glows red when bit errors occur.
2. When not in test mode (green “Test” LED is off), the error LED is used to indicate
an RTS streaming condition. (See Section 5.2) for information on the anti-
streaming circuitry.
3. The “Error” LED is also used to detect line quality as depected by the following:
A. The improper use of flat (non-twisted pair) cable to connect the modems.
B. One or more broken wires in the 4 wire twisted pair cable.
C. The use of low quality twisted pair cable to connect the modems.
D. Broken or corroded connector.
Note In detecting line quality the “Error” LED indicator is designed for 4 wire twisted
pair cable only, and may not function properly with two wire cable.
Setting Up The “Error” LED To Test Cable Quality
If there is any question as to the quality of your line we recommend the following test:
1. Disconnect both local and remote modems from their RS-232 interface. Make
sure “TD”, “RD” and “RTS” LEDs are lit red.
2. Set input impedance of both modems to 200 ohms. (S3-1 “On”, S3-2 “Off”).
3. For ME475A-R2 , set data rate on both modems for 9.6 kbps .
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.
Reading The Test
1. 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.