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168
CHAPTER 4
Using the Gateway
Analog Input
Pulse Counter
Digital I/O
Internal Input
The analog input is provided for connecting analog sensors deliv-
ering a voltage of 0 - 2.5V or a current of 4 - 20 mA converted to a
voltage to the analog pins of the connectors.
Note: The "4 - 20mA" setting assumes that you use the Adcon
A502 current-to-voltage converter which converts a current
of 4 - 20mA to a voltage of 0.4 - 2.0V. If you want to use a
different converter, you have to select "0 - 2.5V" as sensor
type and manually calculate the proper "conversion range"
settings to reflect the physical values the sensor would have
for converted voltages within the range of 0 and 2.5V.
This type of sensor can be used, e.g., to measure the rotation
speed of an engine or to count the hits on a target.
A digital I/O allows to connect digital sensors as well as digitally
controlled actuators.
Digital sensors deliver measurements in form of binary data
streams to the digital pin of the connector.
Digital actuators are driven by binary data streams provided by the
digital pin of the connector. An actuator is a mechanical or electri-
cal device for moving or controlling a mechanism or system. The
actuator is usually a physical mechanism but also refers to an artifi-
cial agent.
Most RTUs, the Wireless Modems and the Gateways are (or can be)
equipped with built-in sensors ("internal sensors"). These sensors
serve especially the purpose to watch the battery or supply voltage
as well as the internal temperature of the respective devices. By
default, the actual values of these sensors do not correspond to
the definitions displayed in the "State information" windows. If,
however, the output of these sensors is to be recorded, it is neces-
sary to define these internal sensors as separate sensor types. By
that, the measurements can be evaluated as those from any other
sensor.
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