ATL Telecom OM25 - Manual (Page 17)

17
ATL User Guide
OM25 O Optical M Modem
5
5.1.5 ENABLE LOOPS
When OFF, loop activation via control lines 140 and 141 is disabled. Also incoming V54 patterns
from the fibre are ignored. This allows end to end loop activation in tandem sections. For example,
the two modems connected by an adaptor cable in Fig 8 would have this option set to OFF, so that
the far left-hand modem could set a remote loop on the far right-hand unit via V54.
Loop activation is still possible via front panel / VT100.
5.1.6 FUNCTIONAL OPERATION
When circuits 105 and 109 are being transferred across the link (End to End signalling ON), the
behaviour is as follows:
Table 1 - V35 operation
'Tx sig' refers to the state of the signalling bit sent on the fibre to the remote end. Similarly, 'Tx
data' refers to the state of the data sent on the fibre to the remote end.
'Rem' is used to denote the state of the appropriate signal at the remote end.
For '106 Set On', 106 is ON in all cases. This is the factory default. When 106 is following 105,
there is a delay of 16ms in the OFF-to-ON transition.
For '107 Set On', 107 is ON in all cases. This is the factory default.
For '109 Set On', 109 is ON in all cases. This is the factory default.
When circuits 105 and 109 are not transferred across the link (End to End signalling OFF), 109 and
Tx sig are ON in line 5. This is the factory default.
Switching circuit 140 ON triggers a V54 sequence to activate a remote loop. Circuit 141 activates
a local loop.
Circuit 142 is active when local loop or loopback is active and also at both ends when remote loop
is active.
Conditions V.35 Outputs Line Outputs
105
Loop
Back
Loc
Loop
In
Sync
Case 106 104 109 107 Tx Sig Tx Data
X Off On X 1 105 103 105 On Off 1
X On On Yes 2 105 103 105 On Rem 105 Rem 103
X On Off Yes 3 Off 1 Off Off Rem 105 Rem 103
X Off Off No 4 Off 1 Off Off X X
X Off Off Yes 5 105
Rem
103
Rem
105
On 105 103