4.3811.00.000_US-Anemometer-DSP_eng.doc
14 - 26
021511/10/06
After the access key has been changed, the ULTRASONIC transmits a response which contains
not only the parameter input but also the access mode.
After parameters have been changed with the key '00001' or '00234', the ULTRASONIC must be
reset to the locked state with the command 00KY00000.
Example:
00KY00001
USER ACCESS
Response from ULTRASONIC
!00KY00001
Response
from
ULTRASONIC
00AV00005
Change in averaging time
00KY00000
WRITE PROTECTED Response from ULTRASONIC
!00KY00000
Response
from
ULTRASONIC
7.1.4 Device ID
The device ID specifies the address to which the ULTRASONIC is to respond during serial
communication. The ID is determined on startup via the external signals at PIN 1, PIN 4 and PIN 2
(ADIO). The device ID lies in the range from 0..7. Every telegram from the ULTRASONIC starts
with the device ID. Under certain conditions this provides for bus mode, see 7.1.5
Bus mode.
On interrogation the device ID 99 is a generic ID. If this ID is used on interrogation, devices transmit
a response, regardless of the ID selected.
7.1.5 Bus mode
The concept of ID-based communication allows ULTRASONICs to be operated in a bus system.
In bus mode there are no restrictions on parameterisability and program upload. A station can also
be provided with a new program in bus mode for a specific purpose. With an update the program
update must be performed for every ULTRASONIC.
7.2 Data
acquisition
The main function of the ULTRASONIC firmware is data acquisition and preparation. For data
acquisition sound impulses are transmitted by the sensors in a clockwise direction and received by
the sensor opposite. The propagation time measured is a measure of the velocity. A measuring
cycle is complete when every sensor has performed transmit and receive once. The complete data
record is then time-stamped and passed on to the next level. After the plausibility check the
individual components are calculated and written to the averaging buffer (see 7.2.1
Averaging).
For a resulting wind velocity < 0.1m/s the wind direction and wind velocity are set to zero. The wind
direction 0° is reserved for no wind. If the wind direction is equal to zero with WV > 0.1m/s, the
interface outputs 360°.
The last valid instantaneous value of the wind velocity is always used as the output value for this
criterion.
7.2.1 Averaging
Given the high data acquisition rate averaging is recommended in most cases. The averaging
period is set to 1 second with this device version.
It is a basic rule that only valid values are written to the averaging puffer. The size of the buffer is
not determined by the number of data records but by the difference in the time stamp between the
first and last data record. As a result any missing measured values do not influence the averaging
result. The content level of the averaging buffer is shown in the status value of the ULTRASONIC.
