Gp 36 Extloop Signal - Xerox FaxCentre F110 Service Manual

GP 36 EXTLOOP Signal

During FCU Off-Hook, the terminal equipment is connected to the line, and the external phone
completely disconnected, so no external phone detection is possible.
During terminal equipment On-Hook (HOOK = 0, PD = 0), the external terminal equipment is con-
nected to the line by LA2, LB2. If the external terminal equipment goes Off-Hook (e.g. by lifting the
Handset) it draws a loop current from the network (I
the Loop Detection Component and a status (EXTLOOP) signal is activated as long as the exter-
nal equipment is Off-Hook and the internal is disconnected
If the external terminal equipment is connected with the line (HOOK = 0, PD = 0) (going Off-Hook),
a valid loop current has to be drawn to established a valid connection.
Loop Current
min. Loop Current
threshold
Idle Loop Current
FaxCentre F110
LA
PSTN
Network
LB
External On-Hook
[mA]
No External Loop
EXTLOOP
Ext_Loop
LB2 LA2
I
Ext Loop
0
I 0
Line
LIU_HOOK
1 PD
U
I
Line
IntLoop
Terminal
Equipment
External phone On Hook
Figure 1
External Off-Hook
External Loop
Current settling
Figure 2
12/04
General Procedures / Information
). This current change is sensed by
Valid External Loop Current
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