Specifications

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Operation
checkout procedures for the data terminal. Also, check the RS-232 interface
cable between the terminal and the ME670A.
Remote Digital Loopback (RDL)
The Remote Digital Loopback (RDL) test checks the performance of both the local and
remote ME670As and the communication link between them. Any characters sent to
the remote ME670A in this test mode will be returned back to the originating device.
For example, characters typed on the keyboard of the local terminal will appear on the
local terminal screen after having been passed to the remote ME670A and looped
back. To perform an RDL test, follow these steps:
1. Activate RDL. This may be done in two ways: first, by moving the front panel
toggle switch UP to “RDL”. Second, by raising pin 21 on the RS-232 interface
(Note: Make sure SW2-8 is OFF).
2. Perform a BER (bit error rate) test on the system.
3. If the BER test equipment indicates a fault, and the Local Analog Loopback test
was successful for both ME670As, you may have a problem with the twisted pair
line between the modems. Make sure you check the twisted pair line for proper
connections and continuity.
Using the V.52 BER Test Independently
The V.52 BER test can be used independently of the V.54 loopback tests. This
requires two operators: one to initiate and monitor the test at the local ME670A, and
one at the remote ME670A. To use the V.52 BER test by itself, both operators should
simultaneously follow these steps:
1. Locate the “511/511E” toggle switch on the front panel of the 1040 and move it
DOWN. This activates the V.52 BER test mode and transmits a “511” test pat-
tern to the other unit. If any errors are present, the receiving modem’s red “Error”
LED will blink sporadically. Note: For this test to function, the “511” switch on
both ME670As must be on.
2. If the test indicates no errors are present, move the V.52 toggle switch UP, acti-
vating the “511/E” test with periodic errors present. If the test is working properly,
the receiving modem's red “Error” LED will light continuously. A successful
“511/E” test will confirm that the link is in place, and that the ME670A’s built-in
“511” generator and detector are working properly.