Hi Siimone: Are you talking about the check sum at the end of the string (which will only tell you if the data string was received correctly) or the actual instrument status word? If you're interested in the quality of the data, you should look at the status word. Actually, there are a total of 6 status words. As the manual states, the string coming from the anemometer is: , StaA, StaD, Wc1, Wc2, Wc3, C,T,... ,chksum, The first part of the Status is the "address". This will be a number between 1 and 6 telling you which particular status word follows (StaD). This will increment each output period and loop around. IF there is an instrument error, then the address will be 0 and the proper error code will be output. The users manual gives a complete description of these codes that you can interpret as you need. If you are only interested in the data TRANSMISSION quality, you can do an XOR of all the bytes between the and the characters. That should match the check sum (byte after the ). In my experience (I've used R3's for about 12 years now) has been that the data transmission never gives a problem. I use these for eddy covariance work and never pay attention to the check sum, only the actual instrument status. Good Luck!
Hi Siimone: Are you talking about the check sum at the end of the string (which will only tell you if the data string was received correctly) or the actual instrument status word? If you're interested in the quality of the data, you should look at the status word. Actually, there are a total of 6 status words. As the manual states, the string coming from the anemometer is: , StaA, StaD, Wc1, Wc2, Wc3, C,T,... ,chksum, The first part of the Status is the "address". This will be a number between 1 and 6 telling you which particular status word follows (StaD). This will increment each output period and loop around. IF there is an instrument error, then the address will be 0 and the proper error code will be output. The users manual gives a complete description of these codes that you can interpret as you need. If you are only interested in the data TRANSMISSION quality, you can do an XOR of all the bytes between the and the characters. That should match the check sum (byte after the ). In my experience (I've used R3's for about 12 years now) has been that the data transmission never gives a problem. I use these for eddy covariance work and never pay attention to the check sum, only the actual instrument status. Good Luck!
Just as a more practical tip, you only need to look for a 0 in the StaA byte to tell if there has been an instrument error.
In the manual there is a matrix that translate hex code to actual messages. Check which values are to be ignored and count and flag only them. As long as i can remember there are two values that must be ignored.
Trust the gill code, and then you will a lot easier quality control of your data
Thanks David!
I was so concentrated in understanding how to interpret the checksum that I didn't look at the meaning of the other fields! I'll check the StaA for errors, thank you again.
Thank also to you Panagiotis
Simone
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