AFP-400 Installation
PN
50253
:
A2 03/12/96
2-51
Wiring an Isolator Module (ISO-X)
Use a loop Isolator Module (ISO-X) to protect critical elements of the com-
munications 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 latches. 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 isolates the faulty branch from the
remainder of the loop. Once the fault is removed, the ISO-X automatically
reapplies power to the communications loop branch.
Shorts on this branch of an isolated communications loop (NFPA Style 4) are
isolated from all devices installed before the ISO-X and on the continuation
of the loop (shown as dotted line).
ISO-X Overview
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. You can wire the supervised
MMX circuit as an NFPA Style B or Style D Initiating Device Circuit. (Refer to
the MMX-1 wiring diagrams in this section.) MMX-2 addressable modules
monitor conventional, two-wire smoke detectors. Wire MMX modules
according to the following:
Wiring MMX Monitor
Modules
ISO-X
T-Tapped branch off the
communications loop
Continuation of the
Communications Loop
Wiring an ISO-X
You can connect a maximum
of 25 devices between
isolator modules. During a
fault condition, the control
panel registers a trouble
condition for each zone
mapped to the isolated loop
branch.
Isolating Two-Wire SLC
Communications Loops
communications
loop
Continued on the next page...
Communications Loop Connections Connect the Communications Loop
to MMX terminals 1 (-) and 2 (+). The MMX takes 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 the connec-
tion diagrams
NFPA Style D Initiating Device Circuit Connect as shown in the connec-
tion diagrams.
Power The MMX-2 requires an additional connection of 24 VDC filtered,
regulated and resettable power on MMX-2 Terminals 3() and 4(+).
ISO-X
Loop In (-)
Loop In (+)
Loop Out (-)
Loop Out (+)
