UNITS slope offset
psi 4.4
0
feet of water
10.152
0
kPa
30.337
0
cm of water
309.44
0
NOTE: The analog output voltage does take into account the field calibration offset (set by the XE
or XS commands).
Configuring the Operating Mode, Purges, and Sample Averaging
Setting the Operating Mode
In order for the ACCUBAR to control the ACCUBUBBLE and make measurements, the operating
mode
MUST
be set to 64 or higher.
The form of the Command is:
aXOMm!
where a is the address character, XOM is the extended command to set the
operating mode and m represents the operating mode.
The valid values for m are:
0
Bubbler disabled. (Low quiescent power consumption mode for an AccuBubble being used as a
pressure sensor.)
64
Bubbler operation. For analog (-4) units this configures the analog output to be updated only
when an SDI-12 measurement is requested.
72
Bubbler with quadrature output. Quadrature output will only be updated when an SDI-12
measurement is requested. Only relevant for a –3 unit.
80
Bubbler with Analog output, self updating. SDI-12 measurements not required for the analog
output to be updated. Only relevant for 5600-0131-4 and 56-0131-50-2 units.
88 Bubbler with quadrature output, self updating. SDI-12 measurements not required for the
quadrature output to be updated. Only relevant for 5600-0131-3 and 56-0131-50-2 units.
Configuring Analog or Quadrature outputs to update independent of SDI-12
To configure a 5600-0131-3 or 56-0131-50-1 unit to update the quadrature output without an SDI-
12 measurement being invoked, the operating mode of the unit must be set to 88. To configure a
5600-0131-4 or 56-0131-50-2 unit to update the analog output without an SDI-12 measurement
being invoked, the operating mode of the unit must be set to 80. See previous paragraph on Setting
the Operating Mode for instructions.
In addition to configuring the unit to update the output independent of SDI-12, the other parameter
to consider is how often the output needs to be updated. The more frequent that the output is
updated, the more frequent the measurements. This measurement rate is specified through the
pump_cycle parameter of the pump timing command:
aXPT+ppuppump_cycle!
The pump_cycle parameter specifies the maximum time between measurements, it does not impose
a fixed schedule. If the unit receives an SDI-12 measurement command, then a measurement will
be invoked and outputs updated. The next measurement will occur in either pump_cycle seconds or
when the next SDI-12 measurement command is received, which ever occurs first. Since
pump_cycle is the 5
th
parameter of the XPT command, values for the other four must be known to
change the 5
th
. The current values can be determined by issuing the aXPT! command followed by
the aD0! command. The first four returned values after the address can then be used as the first four
parameters when issuing the XPT command to set the pump_cycle time. Issuing the aD0!
command immediately after setting the pump timing will allow verification that the parameters were
22
Summary of Contents for Accububble 56-0131-50-1
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