
Power Usage:
l
Quiescent: 0.25 mA
l
Active: 66 mA
l
Measurement: 120 mA
Measurement time: 15 s
Timeout: 15 s
Probes 1, 2, 3, and 4 are connected to SDI-12 port C1.
The time line in the following table shows a 35-second power-usage profile example.
For most applications, total power usage of 318 mA for 15 seconds is not excessive, but if 16
probes were wired to the same SDI-12 port, the resulting power draw would be excessive.
Spreading sensors over several SDI-12 terminals helps reduce power consumption.
Table 7-1: Example power use for a network of SDI-12 probes
Time into
Measurement
Processes
Command
All
Probes
Awake
Time Out
Expires
Probe
1 (mA)
Probe
2 (mA)
Probe
3 (mA)
Probe
4 (mA)
Total
(mA)
Sleep
0.25
0.25
0.25
0.25
1
1
1M!
Yes
120
66
66
66
318
2–14
120
66
66
66
318
15
Yes
120
66
66
66
318
16
1D0!
Yes
66
66
66
66
264
17-29
66
66
66
66
264
30
Yes
66
66
66
66
264
Sleep
0.25
0.25
0.25
0.25
1
7. Communications protocols
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