User's Manual

MDS 05-6399A01, Rev. D MDS Master Station 75
Table 6-15. Alarm Module LEDs
LED Name Behavio
r
Meaning
ALARM MAJ. RED
On—Major Alarm (Master Station)
ALARM MIN. RED
On—Minor Alarm (Master Station)
ACT A BLUE
On—Radio A Active
Off—Radio A Standby
ACT B BLUE
On—Radio B Active
Off—Radio B Standby
6.5.2 Alarm/Audio Interface
The ALARM/AUDIO Interface on the Alarm/Relay module provides audio signaling and alarm outputs as
shown below.
AUDIO:
 4-wire audio circuits are connected to pins 1 through 4 as shown in Figure 9.
 Terminals 1 and 2 are for transmit audio input with a nominal 600 impedance.
 Terminals 3 and 4 provide a receive audio output with a nominal 600  impedance.
 Pins 5 connects to an external keying source. Shorting pins 5 to pin 7 can key the radio when PTT
LOW is configured in software. When PTT is configured high in software, pulling PTT to 3.3V
keys the radio.
The interface is compatible with an external VOX adapter even though this product features an integrated
VOX circuit with digital threshold control. For applications using the external VOX adapter, 12VDC on
pin 6 can be used to power the external module.
ALARMS:
 Terminals 8 and 9 provide solid state relay contacts that close when a minor alarm is detected.
 Terminals 10 and 11 provide relay contacts that close when a major alarm is detected. You can
redefine these relay contacts using the radio’s software (switched from minor to major alarm
outputs, or vice versa). The contacts are rated for non-inductive loads up to a maximum 60 Volts
(AC or DC) at 1 A.
Analog RSSI:
When enabled in software, an RSSI voltage of 0 to 3V corresponding to -120 to -70dBm is present on this
line.
+12v
6
 
12
Analog RSSI
PTT
5
 
11
Major Alarm -
Rx Audio -
4
 
10
Major Alarm +
Rx Audio +
3
 
9
Minor Alarm -
Tx Audio -
2
 
8
Minor Alarm +
Tx Audio +
1
 
7
Ground
Figure 6-9: Alarm/Audio Connections
(As viewed from outside the radio)