Apogee Instruments PYRANOMETER SP-421 Owner's Manual - Page 14
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Metadata Commands
Identify Measurement Commands
The Identify Measurement Commands can be used to view the command response without making a measurement. The
command response indicates the time it takes to make the measurement and the number of data values that it returns. It
works with the Verification Command (aV!), Measurement Commands (aM!, aM1! ... aM9!, aMC!, aMC1! ... aMC9!), and
Concurrent Measurement Commands (aC!, aC1! ... aC9! , aCC!, aCC1! ... aCC9!).
The format of the Identify Measurement Command is the address, the capital letter I, the measurement command, and the
command terminator ("!"), as follows:
The format of the response is the same as if the sensor is making a measurement. For the Verification Command and
Measurement Commands, the response is atttn<CR><LF>. For the C Command, it is atttnn<CR><LF>. For the High Volume
Commands, it is atttnnn<CR><LF>. The address is indicated by a, the time in seconds to make the measurement is indicated
by ttt, and the number of measurements is indicated by n, nn, and nnn. The response is terminated with a Carriage Return
(<CR>) and Line Feed (<LF>).
Identify Measurement Command example:
3IMC2!
The Identify Measurement Command for sensor address 3, M2 command, requesting a CRC.
30032<CR><LF>
The response from sensor address three indicating that the measurement will take three
seconds and two data values will be returned.
Identify Measurement Parameter Commands
The Measurement Parameter Commands can be used to retrieve information about each data value that a command returns.
The first value returned is a Standard Hydrometeorological Exchange Format (SHEF) code. SHEF codes are published by the
National Oceanic and Atmospheric Administration (NOAA). The SHEF code manual can be found
at http://www.nws.noaa.gov/oh/hrl/shef/indexshef.htm. The second value is the units of the parameter. Additional fields
with more information are optional.
The Measurement Parameter Commands work with the Verification Command (aV!), Measurement Commands (aM!, aM1! ...
aM9!, aMC!, aMC1! ... aMC9!), and Concurrent Measurement Commands (aC!, aC1! ... aC9! , aCC!, aCC1! ... aCC9!).
The format of the Identify Measurement Parameter Command is the address, the capital letter I, the measurement command,
the underscore character ("_"), a three-digit decimal number, and the command terminator ("!"). The three-digit decimal
indicates which number of measurement that the command returns, starting with "001" and continuing to "002" and so on,
up to the number of measurements that the command returns.
The format of the response is comma delimited and terminated with a semicolon. The first value is the address. The second
value is the SHEF code. The third value is the units. Other optional values may appear, such as a description of the data value.
The response is terminated with a Carriage Return (<CR>) and Line Feed (<LF>).
<address>I<command>!
<address>I<command>_<three-digit decimal>!
a,<SHEF Code>,<units>;<CR><LF>
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