Accubar SDI-12 Barometric Pressure Sensor Operations & Maintenance Manual Rev-B 30 Nov 2017
pg. 12
avu
where a is the address, v is the data value and u
indicates the units. Both v and u have the format of a
polarity (+ or -) sign followed by up to seven digits,
including a decimal point. One example of a response
would be
0+1013.25+0
The u indicates the units of the measurement. When u is 0, the value has units of mB(hPa). When u is
1, the units are inches of mercury ("Hg). When u is 9, the units depend on a user entered slope and
offset. u can also take on additional values if a station elevation offset has been entered. The following
table summarizes all the values of u.
0
units are mB (hPa)
1
units are "Hg
2
units are kPa
3
units are mmHg
4
units are Atm
5
units are psia
9
units depend on user-entered scale and offset.
If the station elevation offset is non-zero, then one of the following values of u will be returned:
10
units are mB + station elevation offset
11
units are "Hg + station elevation offset
12
units are kPa + station elevation offset
13
units are mmHg + station elevation offset
14
units are Atm + station elevation offset
15
units are psia + station elevation offset
19
user units with non-zero station elevation offset
(mB + elevation offset)
user scale + user offset
set by XE or XS
Set by XUU
In most cases, you will not set up the recorder to store this units identifier. It is provided in response to
the standard measure command to eliminate confusion as to the computation used to come up with the
final value.
Making a Concurrent Measurement (C command)
The command to tell an ACCUBAR
®
to make a concurrent measurement is:
aC!
where a is the address character, and C is the
command to make a concurrent measurement
The concurrent measurement command was first defined in version 1.2 of the SDI-12 specification.
Therefore the data recorder will have to be SDI-12 version 1.2 or higher compliant before it can be
