User’s Guide ______________________________________________________________________
100 _________________________________________________________________ M211840EN-C
SDI-12 Protocol
There are two modes available for providing the functionality of the
SDI-12 v1.3 standard.
The lowest power consumption is achieved with the Native SDI-12
mode (aXU,M=S), as it makes measurements and outputs data only
when requested. In this mode all the commands presented in this
chapter are available except those for the continuous measurement.
In the Continuous mode (aXU,M=R) measurements are made at user-
configurable update intervals. The data is outputted on request. In this
mode all the commands presented in this chapter are available.
For changing the message parameters, units and other settings, see
Chapter 8 Sensor and Data Message Settings, on page 127.
In the Native SDI-12 mode (aXU,M=S) the transmitter is in idle state
most of the time (power consumption < 1 mW). More power is
consumed only during the measurements and data transmit requested by
the host device.
In particular, wind measurement typically consumes 60 mW average
power (with 4 Hz sampling rate), throughout the averaging period. In
the Continuous mode (aXU=M,R) the power consumption is
determined by the internal update intervals of the sensors and wind
averaging time. These have certain limits, so very long measurement
intervals cannot be achieved with this mode. Also the power
consumption between the measurements is about three times that of the
Native mode.
Address Query Command (?)
This command queries the address of the device on the bus.
If more than one sensor is connected to the bus, they all respond,
causing a bus collision.
Command format: ?!
where
? = Address query command
! = Command terminator
To Next Page
Loading...
