AFP-200 Instruction PN 15511:F2 10/11/99 33
2.7.1 The Isolator Module
The loop isolator module (ISO-X) is used to protect critical elements of
the communications loop from faults on other branches or sections of
the loop. The ISO-X continuously monitors the circuit connected to
terminals 3 (–) and 4 (+). Upon power-up, an integral relay is latched
on. The ISO-X periodically pulses the coil of this relay. A short circuit
on the loop resets the relay. The ISO-X sees this short and disconnects
the faulted branch by opening the positive side of the loop (terminal 4).
This effectively isolates the faulted branch from the remainder of the
loop. Once the fault is removed, the ISO-X automatically reapplies
power to the communications loop branch. Figure 2-20 illustrates the
use of an ISO-X on a two wire communications loop meeting NFPA
Style 4 requirements; Figure 2-16 shows a four wire loop meeting
NFPA Style 7 requirements.
Note: The maximum number of devices that can be connected to an isolator module is 25. During a fault
condition, the control panel will register a trouble condition for each zone mapped to the isolated loop branch.
2.7.2 The Monitor Module
The MMX-1/MMX-2 Monitor Module is an addressable module that monitors conventional, alarm initiating
devices. It includes a magnetic test switch located near the center front of the module. The supervised MMX
circuit can be wired as an NFPA Style B or Style D Initiating Device Circuit. Refer to Figures 2-22 and 2-24
for MMX-1 wiring diagrams. The MMX-2 addressable module monitors conventional, two-wire smoke
detectors. Refer to Figures 2-23 and 2-25.
Communications Loop Connections
Connect the communications loop to MMX terminals 1 (–) and 2 (+). The MMX occupies one module address
on the loop. Use the rotary switches on the MMX to set the module to the required loop address.
NFPA Style B Initiating Device Circuit
Connect as shown in Figure 2-22 and 2-23.
NFPA Style D Initiating Device Circuit
Connect as shown in Figure 2-24 and 2-25.
Power
The MMX-2 requires the additional connection of 24 VDC filtered, regulated and resettable power on MMX-2
terminals 3 (–) and 4 (+).
Figure 2-20 Isolating Two Wire SLC Communications Loops
Shorts on this branch of an isolated
communications loop meeting NFPA Style 4
requirements, will be isolated from all
devices installed both upstream of the
ISO-X and on the continuation of the loop
(shown as dotted line).
Loop In ()
Loop In (+)
Loop Out ()
Loop Out (+)
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