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SDMS40 error code -907 and -921

--dd-- Feb 5, 2020 09:25 AM

I'm doing some testing of the SDMS40 in my office, but I have big problems to make the sensor measure correctly. The sensor is installed 1600mm above the floor approximately 15 deg from vertical. I run the example program for SDI-12 in the manual. I start the program and force a calibration by setting the 'Calibrate_Flag' to true. The sensor does its thing and the values shows 0 +/- 2mm. 

1) Can I read the calibration values? It would be preferable to be able to confirm the height and alignment of the sensor.

 Adding a 12 mm foam-plate on the floor gives a "Snow depth" of 12-19mm. All fine... But when I add a 200mm box under the same plate I get -907 for the Snow_depth_avg and -921 for all the point values.

 2) Is '-907' and '-921' some kind of error code, is this explained somewhere in the manual?

 Trying with the same plate on the floor but with a slight angle. Now I get -921 for half of the point measurements and 12-44mm for the rest.

 3) Does this mean that the sensor would not work if the snow surface are not perfectly parallel with the reference surface?

 The feature to automatically retrieve the snow depth is probably preferred by some, but I have a habit to log raw data if possible. Also, I'm forced to install the sensor during wintertime when we have approximately 2m of snow and the reference surface is somehow diffuse since this location is in a mire.

 4) Can I change the settings/program to log the vertical distance from the sensor to the surface, instead of the calculated snow depth?

--dd-- Feb 5, 2020 09:50 AM

...also, I get no respons when using the aXHxx! and aXGxx! commands.

'SDI12Recorder(SDI_Calibrate_Return,SDI12_port,SDMS40_SDI_INPUT,"XH3000!",1,0,-1,1) 'TEST sensor hight TEST!!!
SDI12Recorder(SDI_Calibrate_Return,SDI12_port,SDMS40_SDI_INPUT,"XG2000!",1,0,-1,1) 'TEST offset sensor TEST!!!

Please explain how these functions can be used?

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