Detcon Four Channel Relay Card - Manual (Page 5)

4 Channel Relay Card
Four Channel Relay Card Instruction Manual Rev. 1.2 Page 1 of 8
1.0 Introduction
1.1 Description
The Detcon Four Channel Relay Card provides a low cost means of adding gas detection alarms to a fire alarm
panel. The Relay Card is designed to interface up to four analog 4-20mA gas detection sensors and supports
three programmable alarm levels for each channel. Any 4-20mA gas sensor can be used with this card.
The sensor inputs are continuously monitored by an A/D converter and microcontroller. Whenever one or
more of the sensor inputs exceeds a preset configurable alarm level, the appropriate alarm relay is activated.
The relays and alarm levels are configured using DIP switches mounted on the Relay Card. The Relay Card
provides three configurable alarms (Alarm 1, Alarm 2, and Alarm 3) and a Fault alarm.
Each alarm provides a set of dry relay contacts. These relay contacts consist of “Normally Open” (NO),
‘Normally Closed’ (NC), and ‘Common’ (C).
The four relay outputs are associated with:
 Three alarm levels
o Alarm Level 1
o Alarm Level 2
o Alarm Level 3
 Sensor fault
NOTE
An enclosure is not included with The Four Channel Relay Card. The Relay Card must be
mounted in a user-supplied enclosure appropriate for the environment in which it will be
used. Typically, the card is mounted inside a fire alarm controller enclosure.
1.2 I/O Connections
1.2.1 Power Input
The Relay Card operates using a supply voltage from 12 to 28VDC. Power connections are made via a 2 pin
connector in the lower left corner of the Relay Card (Figure 1). This is a 2 pin connector (Detcon p/n 306-
175701-900).
1.2.2 Sensor Inputs
The Relay Card uses 3-pin connectors (Detcon p/n 306-177984-800) for the sensor connections. The pin out
for these connectors is: GND, sensor power (12-28VDC) and 4-20mA input (Figure 1). The sensor power pin
is connected directly to the supply power connector. The sensor power pin is intended to power a single
sensor (up to 100mA). Any voltage applied to the supply power pin will be present at the sensor power pin on
the sensor connector. If 3-wire sensors are being used, all three pins in the sensor connector are used; if a two-
wire sensor is being used, only power and mA connections are used.
1.2.3 Relay Outputs
Each relay also uses a 3-pin connector (Detcon p/n 306-175701-900) to provide dry relay contacts. The pin
out is for the relay connectors are: Normally Open (NO), Common (C), and Normally Closed (NC) (Figure 1).
The relays are rated at 5A 30VDC or 250VAC.