Xylem SIT65 SATELLITE INTERNET TELEMETRY - Manual (Page 7)

Global Water Instrumentation
7
Digital Control Outputs
There are up to two control outputs available that can be used to remotely control
pumps, valves, lights, etc. These are open-collector outputs that source current to
ground with a maximum of 100mA per channel. Driving larger loads requires a relay
or some other type of switching device. The outputs are protected from driving
inductive loads. Enabling the use of these output channels is a factory
programmable option only.
Access to the control outputs is through a 6-pin polarized connector on the controller
board. If the system is ordered with any control outputs enabled, a matching
connector is provided. This connector has three wires, red is connected to the
12VDC power supply continuously, purple is the output for channel one and white is
the output for channel two. If any high current 12 volt power supply connections are
required, they should be tied directly to the battery terminals or some other low
impedance power or ground source. High switching currents should not be sent
through the controller board.
The control outputs can be turned on and off via commands sent through one of the
databases and the current status of the outputs is shown in all transmitted data.
The radio modem must be turned on to receive the control commands from the
satellite. In cases of low battery voltage, the radio may be shut off by the power
management system to conserve power and will not receive any transmissions.
More about the power consumption is discussed in another section of this manual.
In solar powered systems, care must be taken to ensure that the system will have
sufficient power at the time access to control outputs is needed. With AC powered
systems, power failure must also be considered, although the battery may provide
backup power for several hours or more depending on configuration.
There is a variable time delay between the control command being sent and the time
that action is taken; this is called the latency time. Global Water has no over latency
time, the operation of the Orbcomm satellite network or any of the servers involved in
relaying data to or from our database. While the transmission of sensor data and
commands is reliable, it’s possible that gaps in transmissions could occur and cause
commands to be delayed or missed entirely. It is strongly recommended that the
control outputs not be used in cases where life or property could be
threatened by the failure of the outputs to operate. Global Water is not
responsible for damage caused by failures when using this feature.