Sierra Wireless AirLink RV50 Series, Hardware User'S Manual

Page: 38 / 78

AirLink RV50 Series Hardware User Guide
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Analog Input
You can use the green wire to connect Pin 4 to an analog sensor. As an analog
input (voltage sensing pin), the gateway monitors voltage changes in small
increments. This allows you to monitor equipment that reports status as an
analog voltage.
Pin 4 detects inputs of 0.5 – 36 V referenced to ground. When used with a sensor
to transform values into voltages, the pin can monitor measurements such as
temperatures, sensors, or input voltage.
Figure 3-12: Analog Input
Data sampling is handled by a dedicated microprocessor. In order to filter noisy
signals, twenty measurements are taken over a 250 ms interval and they are
averaged to generate a sample. If the change since the last sample is significant,
a notification is sent to the CPU for updating the current value displayed in the
user interface and for use by Events Reporting.
Changes are considered significant if the change is 150 mV or more. If there has
not been a significant change to the parameter being monitored, the CPU reads a
sample every 2.5 minutes, which detects small changes.
Figure 3-13: Analog Input Sampling and Reading
RV50
Series gateway
Off (default)*
Pin 4
Solar panel or battery
Resistor
V
in
Z
in
= 10 k Ω
Protection
circuitry
Internal Pull-up
Resistor
Output Off (default)*
* Configurable on the ACEmanager I/O tab
Table 3-7: Analog Input
Pull-up Minimum Typical Maximum Units Comments
Off Analog Input Range 0.5 — 36 V —
Analog Input Accuracy -1.5% 0.50% 1.5% — —
Microprocessor
CPU
Sample every 250 ms,
Reading from the CPU
Updates UI
Events Reporting
When a reading is received,
based on 20 measurements
when change is significant
or 2.5 minutes has passed
with no change
Pin 4
Analog input