Belar Sentry 16 Audio & Status Alarm System




The Belar Sentry 16 is an Audio/Logic monitoring system that continuously scans up to eight audio or program channels and eight logic or status inputs to detect changes in station operating parameters.  It combines single-point monitoring of critical audio channels and equipment status, flexible local and remote alarm capabilities, and a computer interface for remote interrogation.  The Sentry 16 senses changes in audio program levels, phase reversals occurring in the audio chain, and changes in equipment operational (logic) status.

Eight Analog (program) Input Channels, Eight Logic Input Channels; Unit control via front-panel pushbuttons and a sixteen-character alphanumeric dot-matrix display and an RS-232 interface; alarm readout through sixteen front-panel tri-color LED’s, the alphanumeric display window, an audible piezo-electric alarm, dry SPDT contacts from two alarm relays, an open-collector external alarm output, and the RS-232 port.  Out-of-tolerance conditions and alarm functions are set independently in each channel.


Technical Specification

Technical Specification

Analoge Channel Inputs

Channels 1–8:
Double-ended, differential-input with semi-automatic input sensitivity adjustment.

Input Level Ranges: 
−10 dBu to +12 dBu (0.25 Vrms to 3.08 Vrms)
–22 dBu to 0 dBu (0.062 Vrms to 0.78 Vrms)
(The –22 dBu-to-0 dBu range is selected by an internal jumper in each channel.)

Input impedance: 
> 50 kω below 20 kHz

Frequency response:
± ¼ dB, 20–20,000 Hz

Alarm Level Threshold:
10% to 95% of input reference level, user-selectable in each channel.

Alarm Level Resolution:
better than 2% of full-scale
(Alarm level resolution is reduced for the –22 dBu-to-0 dBu input level range.)

Input connector:       
20-conductor removable terminal block with screw-actuated wire clamps.

Logic Channel Inputs

Alarms may be set to trigger on logic highs, logic lows, low-to-high transitions, or high-to-low transitions, by user selection.

Channels 9–12:
Optically isolated, floating logic inputs. Compatible with unloaded TTL-family and 5-V CMOS and HCMOS-family logic with totem-pole outputs.  Schmitt-trigger inputs.

Maximum common-mode DC:
<275 VDC.

Maximum differential input:
< 20 VDC.

Channels 13–16:
HCMOS (5-V) with Schmitt trigger inputs.  Compatible with unloaded TTL-family and 5-V CMOS and HCMOS-family logic with totem-pole outputs.  Internal 10-kω pullup to + 5 VDC.

Required swing:
0.6 VDC for logic low, 3.3 VDC for logic high.

Maximum input:
< 20 VDC.

Input connector:   
20-conductor removable terminal block with screw-actuated wire clamps.


Two Alarm Relays: Alarm Relay and Alarm Timer Relay.  Both relays have dry, form C contacts rated for 28 VDC maximum switched voltage, 500 milliamps maximum switched current, and 3 watts maximum switched power.

External Alarm:   One open-collector NPN transistor, limited to less than +40VDC with respect to the Sentry 16 chassis ground, 50 milliamps maximum collector current, and less than about 250 milliwatts dissipation.


Analog & Logic Input Connectors:
Two, twenty-conductor, removable, clamping screw terminal blocks with 5 mm lead spacing (Weidmuller BLZ series).

Serial Interface:

Unit Interface:
Wizard Standard Interface

1 EIA Rack Unit, 1.75″ H x 16″ D x 19″ W

Power Requirements:
15 watts, 100–240 VAC, 50–60 Hz

Unit Weight:
6.6 pounds, 3.0 kg

Shipping Weight:
12 pounds, 5.5 kg
© Copyright 2004 Belar Electronics Laboratory, Inc. All rights reserved.

New in 2015 – 3 Year Factory Warrant to all Belar Products 

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