Dear all,
I am currently working on a CRBasic software to log both GPS data from a Garmin receiver as well as the outputs from a Licor7500. I am inquirying about which would be the west way to log the latter: probably the easiest way is to log the DAC-outputs on some of the CR1000 channels...is there a program to do that?
Also, should I worry about the synchronization between GPS and LiCor data? Or as long as the sampling interval is the same, it's fine?
Regards
Dear FCarotenuto,
The LI-7500 should have an SDM output. With the SDM output you can use the CS7500 instruction in the CRBasic Program to read in the raw data from the LI-7500. One thing to pay attention to is the inherent delay in the LI-7500 electronics. You kind of elude to this in your question above. In order to align the data from the LI-7500 with other instruments you will need to delay the measurements by the appropriate amount that is programmed in the LI-7500. We used to use a 300 ms delay (or 3 scans at 10 Hz). Please referer to section 3-28 in your LI7500 user manual to see how to set the delay. This is of concern mainly when you are trying to align the data to a sonic anemoeter. Because you are doing a covariance between those two instruments. It is really not of concern with the GPS. Hopefully this information helps a bit. Just to let you know we can sell an older version of our program that will support the LI-7500 and CSAT3 along with a GPS. It will give you the raw data outputs in addition to fluxes that have had the WPL corrections applied. You would still need to use the raw data to apply all other corrections however, using a post-processing software such as EdiRE or EddyPro.
Regards,
Ben
Thank you, Ben, it is very clear!
What it is unclear to me is how to cable the LI7500A through the LI7550 circuit board to the SDM interface on the CR1000. On the LI7550 the SDM has 4 wires (Brown = SDM_EN, White = SDM_CLK, Blue = SDM_DATA, Black = GND)...how do the pair with the SDM bracket on the CR1000 (e.g.: Brown to COM1 Tx, Blue to COM1 Rx, etc.)? How do the address translate to that (the 0 - 14 address of the SDM)? Is there an hardware module that I'm missing needed to interface a CR1000 with an SDM device?
Thanks!
Dear FCarotenuto.
On the CR1000 C1, C2 and C3 are the channels used for the SDM. C1 is the data line, C2 is the clock line, and C3 is the enable line. So you would wire the the SDM from the 7550 in the following way:
C1 Blue
C2 White
C3 Brown
G Black
For the SDM address, you need to connect to the LI-7550 using the LI7500 Software. Under the outputs tab you should see "SDM Address". We have always used 7 in the past and usually set the CSAT3 sonic to SDM address 3. Hopefully that helps.
Best
Ben