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Average, Minimum and Maximum Value/Measurement-time
The SDI-AnalogPLUS module can be configured to return two types of results. If the measurement time „t‟ is
set to 0 (zero), it returns two values: current-level and status byte. If the measurement time „t‟ is greater than 0
(maximum 240), then, on a measurement command, the module will take 10 readings per second for „t‟
seconds and return four results: Average, Minimum, and Maximum value over „t‟ seconds followed by status
byte.
If you have configured just one measurement (which will normally be the scenario), measurement-time can be
set/modified through SDI-12 extended command
aXQTt! (e.g. 0XQT+2!)
If you have configured more than one quadrature measurement, say M3 for current level and M4 for average
level, you can set measurement-time through SDI-extended command
aXQm+X+X+t! (e.g. 0XQ4+X+X+2!)
where 2
nd
and 3
rd
„X‟ is in uppercase and means “don‟t care” Using 0XQS+2! in later scenario will change the
measurement time for M3 measurement, not for M4, i.e. whichever is the first one from M1 through M9.
Status Byte
The last byte in the response to an aD0! command, is the status byte. It will be one of the following values
0:
No errors
64:
The Level has never been Set
128: Shaft Over-speed has been detected
192: BOTH the Level has never been set and a Shaft Over-speed has been detected
Verification and Reading current Set-up
There are 2 options to read set-up
1.
aXQm (1XQ4! in our examples) command which returns
a+o+s+t<CR><LF> or
a+NC<CR><LF> if Mm is not set to measure Quadrature.
2.
aXGm (1XG4) command if you are not sure whether Mm measures Quadrature or something else.
Refer appendix A for description on XGm command.
State of Port
The module supports reading the state of any of the 5 ports. The SDI-12 command to configure this
measurement is
aXSm+p+t!
where,
m: Measurement number (M command number : 1…9)
p : Measurement channel
t : Threshold voltage(0.5Vmin, 4.5V max). Default is 1.25V
Example
If, in the module at SDI-12 address 1, you want M6 measurement to return 1 if voltage on AN3 is
greater than or equal to 1.9 volts and 0 if less than 1.9 volts, use
1XS6+3+1.9!
