Front Panel; Input Circuits - Secutron MR-2900 Installation Manual

1.3 Front Panel

The system controls consist of 12 system switches and a 20
position alphanumeric keypad. The 12 system switches are
factory defined for operations such as alarm acknowledge,
signal silence and system reset. The 20-position keypad is used
for:
• technical functions
• system/detector maintenance
• history recall
• device/circuit disarming
• manual operation of addressable output modules, relay
modules and bell circuits

1.4 Input Circuits

There are seven classes of conventional input circuits
supported by the Control Unit. Not all classes are supported by
all the Conventional Input Circuit Modules. See Table 1: Input
Circuit Module Compatibility on page 4 to determine which
circuits are supported by each module.
Conventional Input Circuits
• "Class A" - This is a 4 wire supervised circuit
supporting normally open contact initiating devices.
Two-wire smoke detectors are not supported by this
type of circuit. A "Class A" circuit requires two of the
input circuits, one for the high loop and one for the low loop.
• "Class B" - This is a 2 wire supervised circuit supporting only normally open contact initiating
devices and using a 470
cannot be used on this type of circuit.
• Smoke Detector - This is a supervised circuit supporting two-wire smoke detectors only. Both
"Class B", using the 3.9K
the Input Circuit Module used (see 1.5 Input Circuit Modules on page 4). Contact initiating devices
cannot be used with this type of circuit. A short is reported as a trouble, not as an Alarm.
• Smoke Detector and Contact Device - This is a supervised circuit supporting two-wire smoke
detectors and normally open contact initiating devices. This circuit is wired the same as a Smoke
Detector circuit. Shorts on this type of circuit are reported as an Alarm, not as a trouble.
• Normally Open - This is an unsupervised 2-wire circuit. Normally Open circuits are always
Supervisory circuits. This circuit is listed by UL for connection to other control equipment through
less than 20 feet of conduit.
• Normally Closed - This is an unsupervised 2-wire circuit. This circuit shall not be used to monitor
fire alarm or supervisory initiating devices. This circuit is listed by UL for connection to other
control equipment through less than 20 feet of conduit.
Note: The Control Unit shows spurious alarms and troubles due to any mismatches between the
programmed circuit classes and the actual field wiring.
Ω
End-of-Line Resistor, model EOL-471. Two-wire smoke detectors
Ω
Resistor (EOL-392), and "Class A" wiring is available depending upon
MR-2900 Installation Manual
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