Wiring the Signaling Line Circuit
32
Document #15668 Rev.I 04/20/98 P/N 15668:I
Style 7 Four-Wire Communications Loop (Supervised and Power-limited)
The 4-wire communications loop meets NFPA 72 Style 7 requirements. By flanking each communications loop
device with a pair of I300 Fault Isolator Modules, each device is protected from short circuit faults that may occur on
other devices. For example, a fault on Zone 02 will not affect Zones 01 and 03. The isolator modules on either side
of Zone 02 will open the loop. Zone 01 will still operate from power on Loop Out and Zone 03 will operate from
Loop Return. Since the MS-9200 will no longer be able to communicate with Zone 02, a trouble signal(s) will be
generated for that device. No T-tapping or branching is allowed on this circuit. The ratings and characteristics are the
same as for a 4-wire circuit meeting NFPA Style 6 requirements.
FIGURE 2-13:
4-Wire Communications Loop
1 2 3 4 5 6
T
B
6
A B B+ A+ B- A-
Shield
Connect Loop Out to TB6-3(+) and TB6-5 (-)
Connect Loop Return to TB6-4(+) and TB6-6(-)
CAUTION! Do not loop wiring under any termi-
nals. Break wire run to maintain supervision.
Note: Terminal designations are
shown for all I300 modules.
I300
Isolator Module
I300
Isolator Module
I300
Isolator Module
I300
Isolator Module
SD300
CP300
BG-10LX
Protected Premises
Zone '02'
Protected Premises
Zone '01'
Protected Premises
Zone '03'
3 4
3 4
1 2
2 1
4 3
2 1
3
4
1
2
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