45
Analog Sensors
2.15
Each of the NetGuardian G5's analog channels must be individually configured to monitor data. The
ADCs (analog to digital converters) support a range of –94 to 94 VDC. There are four alarm trip points
(thresholds) in ascending order: major under, minor under, minor over, and major over. The thresholds
must be set from
Under
to
Over
in either ascending or descending voltage (or current) order. For
example, –10, –5, 5 and 10 VDC corresponding respectively to major under, minor under, minor over
and major over is a valid configuration.
To change any one analog alarm to measure current instead, a dip switch setting must be changed.
Refer to the NetGuardian hardware user manual for details on jumper locations and positions. The
jumper inserts a 250 ohm shunt resistor across the input to convert the sensors current output to volts.
Use ohms law to find the voltage drop across the 250 ohm shunt resistor (multiply the current by the
resistance 250 ohms). Please refer to the operation manual for your sensor to determine any other
conversion factors. This will allow you to correctly set the thresholds for
over
and
under
conditions.
Fig. 2.26.
Analog sensors can be viewed and changed from the Edit > Base Analogs screen
Setting Up Your Alarm:
1. From the
Edit
menu click on the
Base Analogs
link.
2. In the
Description
field enter a description for each analog channel being utilized.
3. Check the
Trap
box if you would like to receive an SNMP trapped when a threshold is crossed for
this channel.
4. Enter the ID of the
Pri
mary and
Sec
ondary pagers/notifications that will receive alarms from this
sensor (0 to disable). Edit these notifications in the
Edit
>
Notifications
menu.
Scaling Your Reading:
The analog alarms are set to measure voltage by default and the thresholds are reported as "native
units." For example, if you were using a sensor with a measurable temperature range between 32° and
131° Fahrenheit (0° to 55° Celsius) and an output range between 1 and 5 VDC, you would configure
your analog channel such that 1 volt represents 32° Fahrenheit and 5 volts represents 131° Fahrenheit.
1. Under the
Unit
column, click on the abbreviated units link (e.g VDC, RH, F, etc.) to convert the
reference units and the native units for that analog channel, see Figure 2.26.
2. Set
Reference 1
(VDC) to the minimum output (in volts DC) of the analog device being configured.
3. In the box to the right of
VDC,
enter an abbreviation for the native units being measured (e.g. RH for
relative humidity, F for ° Fahrenheit, etc.).
4. In the box below the abbreviated native unit, enter the reading that corresponds to the minimum
voltage output entered in the previous step.
5. Set
Reference 2
(VDC) to the maximum output (in volts DC) of the analog device being configured.
6. In the box to the right of
VDC,
enter an abbreviation for the native units being measured (e.g. RH for
Содержание NetGuardian 832A G5
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