Decagon Devices DS-2 Panduan Operator - Halaman 13

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4 COMMUNICATION

DS-2

Communication

The DS-2 anemometer communicates using SDI-12 protocol. This

chapter discusses the speciﬁcs of this method. For more informa-

tion, please visit

http://www.decagon.com/support

for the complete

integrators guide, which gives more detailed explanations and in-

structions.

4.1

The DS-2 anemometer communicates using the SDI-12 protocol,

a three-wire interface where all sensors are powered (white wire),

grounded (bare wire), and communicate (red wire) on shared wires

(for more info, go to www.sdi-12.org). There are some positive and

negative elements of this protocol. On the positive side, multiple

sensors can be connected to the same voltage supply and commu-

nication port on the data logger. This simpliﬁes wiring because no

multiplexer is necessary. On the negative side, one sensor problem

can bring down the entire array (through a short circuit, etc.). To

avoid this problem, we recommend the user make an independent

junction box with wire harnesses where all sensor wires are connected

to wire lugs so sensors can be disconnected if a problem arises. A

single three-wire bundle can be run from the junction box to the data

logger.

The SDI-12 protocol requires that all sensors have a unique address.

DS-2 anemometers come from the factory with an SDI-12 address

of 0. To add more than one SDI-12 sensor to a system, the sensor

address must be changed to some value other than zero and all sen-

sors on the bus must have unique addresses. Address options include

1..9, A..Z, a..z .

There are two ways to set the SDI-12 sensor address. The best and

easiest is to use Decagon's ProCheck (if the option is not available

on your ProCheck, please upgrade to the latest version of ﬁrmware).

SDI-12 addressing can be accessed in the "CONFIG" menu by se-

lecting "SDI-12 Address" and pressing Enter. To change the SDI-12

address, press the up and down arrows until you see the desired