Videotec DCT - Manual (Page 29)

4.2.3.3 Serial tests
If it is necessary to check the keyboard communication channels, there is a simple test to check the integrity of
the serial video output and the telemetry.
Disconnect any devices connected to the VIDEO and telemetry A and B connectors and make the following
test cable, using two telephone cables and two RJjack boxes supplied with the keyboard, then proceed with the
test.
Telephone cable RJjack1 RJjack2 Telephone cable
RS485A white white RS485A
RS485B yellow yellow RS485B
WARNING
This cable is different from the standard connection cable described in § 3.3 - One keyboard per
line: standard connection cable, page 15.
4.2.3.3.1 Autotest procedure
 Connect the cable to the telemetry A and B connectors.
 Make sure the display shows the message B <-------> A
indicating that the two lines are working correctly.
If other messages appear, for example:
B <-------? A,
this means that there are reception/transmission problems in the line or that the cable has not been made
correctly.
Continue with the test, repeating the procedure and connecting the cable between the telemetry A and VIDEO
connectors and then connecting the cable between the telemetry B and VIDEO connectors.
For each line, A, B and V (Video) the autotest result is expressed by the following strings:
?? :
the line is not working and is unable to transmit or receive data
T? : the line is able to transmit but not receive
?R : the line receives but is unable to transmit
OK : the line transmits and receives correctly.
Page 27 of 176 MNVADCT03_0716
RJjack1 RJjack2