VP-4
6
COMMUNICATION
6
Communication
The Decagon VP-4 sensor can communicate using two different meth-
ods, Decagon serial string or SDI-12 communication protocol. In this
chapter we briefly discuss the specifics of each of these communica-
tion methods. Please visit
www.decagon.com/support/literature
for
the complete Integrator’s Guide, which gives more detailed explana-
tions and instructions.
6.1
Digital Communication for Data Logger
SDI-12 Communication
The communications between the VP-4 and the Decagon logger is
automatic and only requires you to select the correct sensor configu-
ration for the sensor port. When a Decagon logger applies excitation
voltage, the VP-4 sensor makes a measurement. Within about 550 ms
of excitation three measurement values transmit to the data logger
as a serial stream of ASCII characters complete with checksum and
sensor identification. Please see the VP-4 Integrators Guide.docx
document available from
www.decagon.com/support/literature
for
more information on this communication protocol.
SDI-12 Commands
Table 2 provides SDI-12 commands that the VP-4 sensor responds
to. The sensor address is shown as a. If a ? is substituted for a all
addresses respond.
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