DuraComm PSDA-MU1, Owner'S Manual

Page: 13 / 47

Page 13 of 47
The left side connects to the Fire Alarm Panel (FAP). The separate EOL connector allows the FAP to
detect when there is a bad connection to the annunciator board or when the connector is accidently not
replaced. Full FORM C connections are available for 6 channels, 1 antenna channel (50 Ohms), a system
fault channel and a system trouble channel.
The connector on the right has two positions for each of the 7 monitored lines to the BDA alarm
contacts. The annunciator assumes the contacts are normally open for a non-trouble or non-alarm)
situation. 10 Kohm EOL resistors (supplied mounted on the connector) should be used at the equipment
termination end for channels 1-6, and a 50 Ohm EOL termination should be used for the antenna
channel. A 51 ohm resistor is mounted on the connector for monitoring a relay contact instead of an
antenna line, if desired. (
Bias tees, as well as connector and 50 ohm load must be purchased
separately.)
Channels 1 through 6 are floating relative to earth ground due to an isolated 12VDC power supply
module, and normal operation is not affected when either the high or low side of any channel has a
short to earth ground. If both lines (Supply voltage and test point) are shorted to earth ground, the
result is a short across the wires, like an alarm contact, so it will show a Trouble alarm (red light).
Multiple ground faults across multiple channels could cause unpredictable results.
If, for some strange reason the test point supply or test point are shorted to the internal ground, it will
show a fault (blue light).
The antenna monitoring channel (channel 7) is also isolated from earth ground. The test point for the
antenna channel is connected to earth ground when connected to the antenna coax shield. A short
between the center conductor of the coax and the shield will create a trouble alarm.
The 5 V and 12 V internal power supplies are isolated from each other as well.
The SITEGUARD uses its fully Isolated analog channels to monitor the test point voltages and compare
the reading to alarm values. IF the voltage is above the upper alarm limit, it will set a corresponding
digital output which causes the annunciator board to report a trouble (red). These alarm levels are
adjustable if required, but the default setting allows for a large amount of cable loss. Setting the alarm
voltage too close to the normal test point voltage may cause false alarms due to electrical noise,
temperature variations or other variables. Setting a higher measurement average on the Sensor Setup
page, or alarm duration on the Alarm Setup page may help with the random effects, but this could have
negative effects with alarm reporting, especially for self-test.
The Fault voltage reference is set for channels 1-6 by Digital-to-Analog (DAC) output 1 on the
SITEGUARD and can be remotely programmed if needed. It is set to 1 V at the factory.