The signalk_client command must be run from a console.

<code>
pi@raspberrypi:~ $ signalk_client -h
usage /usr/local/bin/signalk_client [host] -i -c -h [NAME]...
-i print info about each value type
-c continuous watch
-h show this message
</code>

You can run with no arguments to retrieve all available values.

To receive only the voltage:
<code>
pi@raspberrypi:~ $ signalk_client servo.voltage
</code>

To continuously receive the imu heading:
<code>
pi@raspberrypi:~ $ signalk_client -c imu.heading
</code>