Sdi-12 Measurement Commands - Young ResponseONE 91000 Instructions Manual

5.1.1 ASCII
ASCII output format provides continuous measurement data in text
format at any of the available baud rates.
The wind measurement in ASCII output appears either in POLAR
(default) or CARTESIAN UV format. With POLAR format, the wind
speed threshold and wind speed units are user-selectable. With
CARTESIAN the wind threshold is ignored and wind speed units
are always meters per second (m/s).
ASCII POLAR FORMAT
a www.ww ddd.d ss*cc<CR>
where:
a = Sensor address
www.ww
= Wind speed
ddd.d = Wind direction
ss = Status code
* = Asterisk (ASCII 42)
cc = Checksum
<CR>
= Carriage return (ASCII 13)
ASCII CARTESIAN (UV) FORMAT
a uu.uu vv.vv ss*cc<CR>
where:
a = Sensor address
±uu.uu = U-axis wind speed (m/s)
±vv.vv = V-axis wind speed (m/s)
ss = Status code
* = Asterisk (ASCII 42)
cc
= Checksum
<CR> = Carriage return (ASCII 13)
CHECKSUM is a two-character hexadecimal value (in printable
ASCII format) generated by taking the exclusive-or of all characters
up to the asterisk. STATUS CODE shows a non-zero value when the
sensor cannot acquire sufficient samples or a measurement error has
occurred. See APPENDIX C for more information on status codes.
5.1.2 ASCII POLLED
ASCII POLLED is like ASCII format described above except just
one serial output string is sent for each polling command received.
The polling command is Ma! where 'a' is the sensor address (valid
characters: 0-9, A-Z, a-z). The default address is '0' (ASCII 48).
5.1.3 RMYT
RMYT is a 6-byte binary data format sent at 9600 baud using RS-485
OUTPUT ONLY mode. It is for use with the YOUNG Model 06201
Wind Tracker.
5.1.4 NMEA
NMEA format provides continuous measurements in standard
NMEA marine sentences at 4800 baud. The ResponseONE must be
connected to a NMEA-capable device. Specific details of the NMEA
data string are below:
91000-90(B)
NMEA FORMAT
$WIMWV,ddd,R,www.w,u,A*cc<CR><LF>
where:
WI = Device type (weather instrument)
MWV = Wind direction and speed
ddd = Wind direction (degrees)
www.w = Wind speed
u
= Wind speed units
A
= Data status code: A=valid, V=invalid
* = Asterisk (ASCII 42)
cc = Checksum
<CR><LF> = Carriage return,Line feed (ASCII 13,10)
CHECKSUM is the two-character printable hexadecimal value
generated by taking the exclusive-or of all characters between '$'
and '*'.
5.2 SDI-12
SDI-12 stands for serial data interface at 1200 baud. It is often used
to interface battery powered data recorders with microprocessor
based devices designed for environmental data acquisition. SDI-
12 is typically used when low power usage is required. The SDI-12
device normally remains in a low power, standby state until it is polled
at which time a measurement is sent. SDI-12 can effectively address
multiple sensors on the same cable.

5.2.1 SDI-12 MEASUREMENT COMMANDS

Model 91000 uses the SDI-12 (v1.3) serial communication protocol
to initiate measurements and set sensor operation parameters.
The default sensor address is 0 (zero), and can be changed to
any valid single-character value if needed. Additional details about
the SDI-12 protocol may be found at www.sdi-12.org.
After initial power-up with 12 VDC, the sensor is in a low-
power standby state with a quiescent current of 4.2 mA. A valid and
properly addressed SDI-12 command wakes the sensor to initiate a
measurement, set or check operating parameters. After command
processing has finished, the sensor returns to the low-power standby
state.
SDI-12 'M' or 'C' commands initiate a measurement. The sensor
response message indicates the maximum time needed before
the measurement is ready, and data values will be available. The
maximum time ranges from 1 to 5 seconds depending on the Sample
Count.
If an 'M' command initiates a measurement, the sensor sends a
Service Request when the measurement is ready to be retrieved.
When the polling device receives the Service Request it then sends
a 'D' command to request measurement results from the sensor.
With 'C' commands, no Service Request is sent, and the polling
device must wait the full delay time before sending the 'D' command
to request the measurement.
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S = mph
N = knots
K = kmph
M = m/s