Secutron MR-2312-AT Installation Manual download pdf (Page 9)

Wiring Instructions

3.0 Wiring Instructions

The RS-485 Wiring to the

MR-2312-AT Module is

recommended to be

twisted shielded pair as

shown in the diagram. The

wire gauge may be:

• 22 AWG up to 2000 ft.

• 20 AWG up to 4000 ft.

The RS-485 wiring from

the fire alarm control panel

to the annunciator(s) must

be point-to-point from the

fire alarm panel to the first

annunciator, then to the

next annunciator, and so

on. No star wiring or T-

tapping is allowed. Each

MR-2312-AT Annunciator

Module has a 120 ohm end-of-line resistor on its RS-485 output terminals. This is removed on

all except the last wired module.

The 24 VDC field wiring needs to be of an appropriate gauge for the number of annunciators

and the total wiring run length. Use the Current Drain for Battery Calculations on page 13 to

calculate the maximum current for all annunciators summed together.

Note: All circuits are power limited and must use type FPL, FPLR, or FPLP power

limited cable.

Attention: Accidentally connecting any of the 24 VDC wires to the RS-485 wiring will

result in damage to the annunciator and/or to the fire alarm control panel to

which it is connected.

Table 2 Maximum Wiring Run to Last Annunciator

Total Maximum Current

for all Annunciators

Maximum Loop

Resistance

18AWG 16AWG 14AWG 12AWG

Amperes ft. m. ft. m. ft. m. ft. m. Ohms

0.12 1180 360 1850 567 3000 915 4250 1296 15

0.30 470 143 750 229 1200 366 1900 579 6

0.60 235 71 375 114 600 183 850 259 3

0.90 156 47 250 76 400 122 570 174 2

1.20 118 36 185 56 300 91 425 129 1.5

1.50 94 29 150 46 240 73 343 105 1.2

1.70 78 24 125 38 200 61 285 87 1.0

24 VDC

OUTPUT

RS-485

OUTPUT

RS-485

INPUT

24 VDC

INPUT

24 VDC POWER FROM FIRE ALARM CONTROL

PANEL OR PREVIOUS ANNUNCIATOR

24 VDC POWER TO

NEXT ANNUNCIATOR

RS-485 TO NEXT ANNUNCIATOR

(TWISTED SHIELDED PAIR)

RS-485 FROM FIRE ALARM OR PREVIOUS

ANNUNCIATOR (TWISTED SHIELDED PAIR)

Figure 2 Wiring Diagram

1 2 3 4 5 6 7 8 9 10 11 12 13 14 ... 19 20

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Secutron MR-2312-AT Installation Manual Page 9

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