CS SR50A, Инструкция по эксплуатации

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SR50A-Series Sonic Ranging Sensors
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8.3 SDI-12 Measurements
8.3.1 SDI-12 Addresses
The SR50A can be set to one of ten addresses (0 to 9) which allows up to ten
sensors to be connected to a single digital I/O channel (control port) of an
SDI-12 datalogger.
The SR50A is shipped from the factory with the address set to 0. The address
on the SR50A can be changed by sending an SDI-12 change address command.
The change address command can be issued from most SDI-12 recorders. For
some Campbell Scientific dataloggers, the SDI-12 transparent mode will need
to be entered to change the address.
When it is necessary to measure more than one SR50A, it is easiest to use a
different control port for each SR50A instead of changing the address. If
additional control ports are not available, then the address will need to be
changed.
To change the address of a sensor that has the default address of 0 to the
address of 1 the following command can be sent:
“0A1!”
Only one sensor of the same address should be connected when using the
change address command.
8.3.2 SDI-12 Commands
The SDI-12 protocol supports the SDI-12 commands listed in TABLE 8-2 .
The SR50A needs to be powered for 1.5 s before it can receive an
SDI-12 command.
The different commands are entered as options in the SDI-12 recorder
instruction. The major difference between the various measurement commands
are the data values that are returned. The user has the option to output the
distance to target in either meters or feet, or to include the measurement quality
numbers.
If the SR50A is unable to detect a proper echo for a measurement, the sensor
will return a zero value for the distance to target value.
TABLE 8-2. SDI-12 Commands
SDI-12
Command Command Function/Description Values Returned
aM! Distance-Meters D
aM1! Distance-Meters, Quality Number D, Q
aM4! Snow Depth Meters, Quality Number, Temperature SD, Q, T
aM5! Distance-Inches D
aM6! Distance-Inches, Quality Number D, Q
NOTE