Testing your private circuit
Using the Test menu
You can test the circuit and the operation of your NTU by using the
TEST MENU
. You can implement the following conditions, which may help
you isolate faults in either the BT network or your terminal equipment.
All the tests, except the self-test and the lamp test, interrupt data flow.
Operating guide
10
select
to
loop your NTU towards your terminal equipment (see below)
loop your NTU towards the distant end (see below)
run a self-test on the NTU; if the NTU doesn’t pass it locks with
the message and you should report this to the
relevant X-Stream Service Centre
to cause the distant end to provide a loop back – only possible
where the NTU is set for X21 bis working (see below)
transmit binary 1s to the distant end
transmit binary 0s to the distant end
illuminate all lights on the NTU
T: LAMP TEST
T: SEND BIN 0
T: SEND BIN 1
T: REMOTE LOOP
T: SELF TEST
T: LOOPBACK
T: LOCAL LOOP
SELF TEST FAIL
NTU
NTU
Remote site
Local site
Local end
Local end
Digital
network
main link
Loopback
Local
loop
Remote
loop
Local
exchange
Local
exchange
Types of Test Loops
For national KiloStream circuit
