User manual VAISALA WXT520 USER S GUIDE 2008

[. . . ] USER'S GUIDE Vaisala Weather Transmitter WXT520 M210906EN-A PUBLISHED BY Vaisala Oyj P. O. Box 26 FIN-00421 Helsinki Finland Phone (int. ): Fax: +358 9 8949 1 +358 9 8949 2227 Visit our Internet pages at http://www. vaisala. com/ © Vaisala 2008 No part of this manual may be reproduced in any form or by any means, electronic or mechanical (including photocopying), nor may its contents be communicated to a third party without prior written permission of the copyright holder. Please observe that this manual does not create any legally binding obligations for Vaisala towards the customer or end user. All legally binding commitments and agreements are included exclusively in the applicable supply contract or Conditions of Sale. ________________________________________________________________________________ Table of Contents CHAPTER 1 GENERAL INFORMATION . [. . . ] The content of the parameter "Id" is a text string which can be modified by using the Vaisala Configuration Tool only. For more information on changing the settings, refer to the Vaisala Configuration Tool on-line help for the Info field in the Device Settings window. VAISALA _______________________________________________________________________ 75 User's Guide ______________________________________________________________________ Combined Data Message (aR) With this command you can request all individual messages aR1, aR2, aR3 and aR5 with just one command. Command format: aR<cr><lf> where a R <cr><lf> = = = Device address (default = 0) Combined message query command Command terminator Example of the response: 0R1, Dm=027D, Sm=0. 1M<cr><lf> 0R2, Ta=74. 6F, Ua=14. 7P, Pa=1012. 9H<cr><lf> 0R3, Rc=0. 10M, Rd=2380s, Ri=0. 0M, Hc=0. 0M, Hd=0s, Hi=0. 0M<cr><lf> 0R5, Th=76. 1F, Vh=11. 5N, Vs=11. 5V, Vr=3. 510V, Id=HEL___<cr><lf > Composite Data Message Query (aR0) This command is used to request a combined data message with user configurable set of wind, pressure, temperature, humidity, precipitation and supervisor data. Command format: aR0<cr><lf> where a R0 <cr><lf> = = = Device address Composite data message query command Command terminator 76 ___________________________________________________________________M210906EN-A Chapter 7 __________________________________________________ Getting the Data Messages Example of the response (the parameters included can be chosen from the full parameter set of the commands aR1, aR2, aR3 and aR5): 0R0, Dx=005D, Sx=2. 8M, Ta=23. 0C, Ua=30. 0P, Pa=1028. 2H, Rc=0. 00M, Rd=10s, Th=23. 6C<cr><lf> For selecting the parameter set in the response message, see Chapter 8, Sensor and Data Message Settings, on page 107. Polling with CRC Use the same data query commands as in the previous sections but type the first letter of the command in lower case and add a correct threecharacter CRC before the command terminator. For more information about the CRC-computation see Appendix C, CRC-16 Computation, on page 159. Requesting a wind data message with a CRC: Command format: ar1xxx<cr><lf> where a r1 xxx <cr><lf> = = = = Device address Wind message query command Three-character CRC for ar1 command Command terminator Example of the response (the parameter set is configurable): 0r1, Dn=236D, Dm=283D, Dx=031D, Sn=0. 0M, Sm=1. 0M, Sx=2. 2MLFj <cr><lf> where the three characters before <cr><lf> are the CRC for the response. NOTE The correct CRC for each command can be requested by typing the command with an arbitrary three-character CRC. VAISALA _______________________________________________________________________ 77 User's Guide ______________________________________________________________________ Example of asking the CRC for the wind data message query ar1: Command format: ar1yyy<cr><lf> where a r1 yyy <cr><lf> = = = = Device address Wind message query command Arbitrary three-character CRC Command terminator Response: atX, Use chksum GoeIU~<cr><lf> where a tX, Use chksum Goe IU~ <cr><lf> = = = = = Device address Text prompt Correct three-character CRC for the ar1 command Three-character CRC for the response message Response terminator Example of the other data query commands with CRC (when the device address is 0): Pressure, humidity and temperature message query Precipitation query Supervisor query Combined message query = = = = 0r2Gje<cr><lf> 0r3Kid<cr><lf> 0r5Kcd<cr><lf> 0rBVT<cr><lf> 0r0Kld<cr><lf> Composite data message query = In every case the response contains a three-character CRC before the <cr><lf>. For selecting the parameters to be included in the response messages, changing the units and making other configurations of the measured parameters, see Chapter 8, Sensor and Data Message Settings, on page 107. 78 ___________________________________________________________________M210906EN-A Chapter 7 __________________________________________________ Getting the Data Messages Automatic Mode When automatic ASCII protocol is selected the transmitter sends data messages at user configurable update intervals. The message structure is same as with data query commands aR1, aR2, aR3 and aR5. You can choose an individual update interval for each sensor, see Chapter 8, Sensor and Data Message Settings, on page 107, sections Changing the Settings. Example: 0R1, Dm=027D, Sm=0. 1M<cr><lf> 0R2, Ta=74. 6F, Ua=14. 7P, Pa=1012. 9H<cr><lf> 0R3, Rc=0. 10M, Rd=2380s, Ri=0. 0M, Hc=0. 0M, Hd=0s, Hi=0. 0M<cr><lf> 0R5, Th=76. 1F, Vh=11. 5N, Vs=11. 5V, Vr=3. 510V<cr><lf> Example (with CRC): 0r1, Sn=0. 1M, Sm=0. 1M, Sx=0. 1MGOG<cr><lf> 0r2, Ta=22. 7C, Ua=55. 5P, Pa=1004. 7H@Fn<cr><lf> 0r3, Rc=0. 00M, Rd=0s, Ri=0. 0MIlm<cr><lf> 0r5, Th=25. 0C, Vh=10. 6#, Vs=10. 8V, Vr=3. 369VO]T<cr><lf> NOTE Stop the automatic output by changing the communication protocol to polled mode (aXU, M=P). Polling commands aR1, aR2, aR3, and aR5 can be used also in ASCII automatic protocol for requesting data. Automatic Composite Data Message (aR0) When automatic composite data messaging is selected, the transmitter sends composite data messages at user configurable intervals. The message structure is the same as with the composite data query command aR0 and contains a user configurable set of wind, pressure, temperature, humidity, precipitation and supervisor data. VAISALA _______________________________________________________________________ 79 User's Guide ______________________________________________________________________ Example (the parameters included can be chosen from the full parameter set of the commands aR1, aR2, aR3 and aR5): 0R0, Dx=005D, Sx=2. 8M, Ta=23. 0C, Ua=30. 0P, Pa=1028. 2H, Hd=0. 00M, Rd=10s, Th=23. 6C<cr><lf> For selecting the parameter set in the response message, see Chapter 8, Sensor and Data Message Settings, on page 107. Automatic composite data messaging is a concurrent, not an alternate mode to either the polled or automatic modes. SDI-12 Protocol There are two different modes available for providing all the functionality of the SDI-12 v1. 3 standard. The lowest power consumption is achieved with the Native SDI-12 mode (aXU, M=S), as it makes measurements and outputs data only when requested. In this mode all the commands presented in this chapter are available except those for the Continuous measurement. In the Continuous mode (aXU, M=R) measurements are made at userconfigurable update intervals, see Chapter 8, Sensor and Data Message Settings, on page 107. In this mode all the commands presented in this chapter are available. For changing the message parameters, units and other settings, see Chapter 8, Sensor and Data Message Settings, on page 107. In the Native SDI-12 mode (aXU, M=S) the WXT520 is in idle state most of the time (power consumption < 1 mW). More power is consumed only during the measurements and data transmit requested by the host device. Especially, the wind measurement typically consumes 60 mW average power (with 4 Hz sampling rate), throughout the averaging period. In the Continuous mode (aXU=M, R) the power consumption is determined by the internal update intervals of the sensors and wind averaging time. [. . . ] A sensor must wake up from a low-power standby mode and be capable of detecting a start bit from a valid command within 100 milliseconds after detecting a break. After a data recorder transmits the last character of a command, it must relinquish control of the data line within 7. 5 milliseconds. - - 0505-218 Figure 31 Timing Diagram VAISALA ______________________________________________________________________ 157 User's Guide ______________________________________________________________________ - After receiving the break and the command, the addressed sensor sets the data line to marking at 8. 33 milliseconds and then sends the response (tolerance: -0. 40 milliseconds. ) The start bit of the first response byte must start within 15 milliseconds after the stop bit of the last byte of the command (tolerance: +0. 40 milliseconds). After a sensor transmits the last character of a response, it must relinquish control of the data line within 7. 5 milliseconds (tolerance: +0. 40 milliseconds. ) No more than 1. 66 milliseconds of marking are allowed between the end of the stop bit and the start bit (for example between characters) on any characters in the command or the response (no tolerance. ) This permits a response to an M command to be sent within a 380-millisecond window. Sensors must return to a low-power standby mode after receiving an invalid address or after detecting a marking state on the data line for 100 milliseconds (tolerance: +0. 40 milliseconds). [. . . ]