More Information ‣ Status Flags (page 113) 126.96.36.199 WMT700 Data Message 25 WMT700 Data Message 25 reports wind measurement, sonic temperature, and status data. The checksum is included in the message. WMT700 calculates the checksum by applying 8- bit XOR for all bytes between checksum calculation start point and endpoint. The result is printed as a digit hexadecimal value. The message is in the following format: \ss$\ws,\wd,\wp,\wm,\Ts,\er,\se\sp\cr\lf \ss Checksum calculation start point, not shown in the message $ Fixed text \ws Wind speed, average \wd Wind direction, average \wp Wind speed, maximum \wm Wind speed, minimum \Ts Sonic temperature \er Status code. The code is a decimal number. Each bit corresponds to a status flag. See Status Flags (page 113) \se Checksum calculation endpoint, not shown in the message \sp Print checksum (to verify message integrity) \cr CR (carriage return) \lf LF (line feed) Chapter 5 – Operation 123
Example $03.22,75.29,03.38,03.07,22.13,0,3E Interpretation of the example message: • Wind speed, average 3.22 m/s • Wind direction, average Wind speed, maximum 3.38 m/s • Wind speed, minimum 3.07 m/s • Sonic temperature 22.13 °C • Status code 0 • Checksum: A 188.8.131.52 ROSA - MES Data Message The MES data message 12 is used in the ROSA Surface Analyzer for Roads and Runways system. You can use this data message when WMT700 is connected to the Vaisala ROSA system. This message contains sensor identifications (sids), corresponding data items, and the synchronization characters SOH, STX, and ETX. The lines are ended by CR and LF characters Missing Readings If WMT700 is notable to measure the wind, it indicates a missing reading in the output. The most common reasons for measurement problems are ice, birds, or other foreign objects on the line of measurement. When the WMT700 profile is used, WMT700 indicates missing readings by showing 999 in the data messages. When the WMT700 Data Message 22 is polled, missing readings are indicated with the following response: $999.00,999.00 5.10.4 Error Indication WMT700 provides advanced self-diagnostics for monitoring the status of the wind sensor and the validity of the measurement data. You can use the diagnostics as follows: WMT700 User Guide M211095EN-H 124
• WMT700 checks the status of the internal operational software at each reset by verifying the CRC checksum of the software. The software check is not made periodically it is only made at each reset. If the checksum is incorrect, WMT700 does not start up. If the checksum is correct, WMT700 continues by calculating the CRC checksum of the parameter memory. In case the parameter memory is corrupted, the sensor replies with the text Parameters crc error upon startup. In case the parameter memory checksum is correct, WMT700 replies with the text ready as shown in the example below. >$WMT700 v ready. • To check the status of the wind sensor, include the status code item er in the data message. You need to convert the status code to a binary number to verify the status. An error code does not indicate that the wind data is invalid. • To check that the wind data is valid, include the \va item in the data message. • To check other diagnostics-related data, include the required items in the data message.