Xylem H-5223 - Manual (Page 20)

Figure 2-6 SDI-12 Expanded Connector System
2.2.5 SDI-12 Section
Pins 11, 12, and 13 of the terminal block provide connection points for SDI-12 senors. The
+12Vsw power connection under the SDI-12 section is limited to about one amp so it may be
necessary to connect the SDI-12 sensor power line directly to the battery or to main power. This
excitation can be set to stay on continuously or to be switched on only at scan time.
If this excitation is to be turned on and off at scan time, then it may be necessary to have a warm
up delay after the excitation has turned on before starting to take measurements. The warmup
delay can be in the range of 0 to 9999 milliseconds.
If several SDI-12 sensors are to be connected to the H-5223, it may be necessary to use external
terminal strips to provide enough connection points.
2.2.6 Power Connections
The last two pins at the far right of the terminal block provide the main connection points for
system power and ground.
NOTE: If the battery voltage is below 11.0 volts the GOES transmissions will stop. If the
battery voltage is below 9.5 volts, data logging will stop.
NOTE: When connecting to or removing the wires from these connection points, it is important
to remove the terminal block from the H-5223 first, or to have the other end of the
wires disconnected from the battery.
NOTE: Make sure scanning is turned off on units not being used to help preserve backup
battery life.
2-6 Hardware Options and Installation
H-5223