CindiA,
It still isn't right. You are probably looking at your Relative pressure on your display console and that may match. But for CWOP your Relative pressure is not what is used. When sending data to CWOP what is used is your Absolute pressure in conjuction with your elevation. Therefore it is important that you have set things up correctly with Absolute pressure and your elevation.
Step 1First is to determine your elevation. I like to use the following website to determine elevation.
https://www.freemaptools.com/elevation-finder.htmUsing that website your elevation is 236 meters. We need to use the metric system for better results. This goes not just for elevation but also for barometric pressure. Your console will be more precise while using metric barometric pressure which is measured in hPa. After calibration if you prefer to see inHg units you can switch back and all calibration settings will stay. So, calibrate with metric and then switch back to Imperial units if you prefer.
We then take the 236 meters and I'm going to add 1 meter to that to account for the fact that your barometric sensor is at least 1 meter off the ground. It is inside of your display console in the WS-2902. You can make adjustments to my estimates if you prefer.
Your total barometric sensor elevation of 237 is entered into the following online calculator to figure out what the difference between your Relative pressure and Absolute pressure should be. Do not change the standad temperature of 15°C nor the standard pressure of 1013.25 hPa as these are required numbers to get a good mean value for your offset.
https://keisan.casio.com/exec/system/1224579725After entering just the 237 meters into the Keisan Casio calculator we hit the execute button and the results show atmospheric pressure of 985.24 hPa. We then subtract that number the standard pressure which is 1013.25.
1013.25 - 985.24 = 28.01
standard pressure (1013.25) - the calculated standard absolute pressure for your elevation = the offset or difference between both pressures.
We have now caluclated that 28.0 hPa is the barometric offset between Relative Pressure and Absolute Pressure. What this means is that 28.0 hPa is by how much your Relative and Absolute pressure will differ....always! I recommend switching your console to show hPa for pressure to enter this difference in. Don't worry about how much it will mess up your Relative pressure. We will fix that in the next step. What is important is that Whatever shows for Relative Pressure is exactly 28.0 hPa from whatever it shows is Absolute pressure. Essentially we are now giving the display console the information that it needs because 28.0 hPa is indicative of 237 meters of elevation.
That concludes Step 1...which is essentially entering in this offset which tells the console what your elevation is.
Step 2Now for Step 2 you look to see what is shown for Relative pressure on your display console. You compare that to your local METAR KLCK and/or KTZR. The METAR shows hPa also...so that keeps it in metric..which is good. Before you touch your console again though....all you need to know is how much off you are. If you are say 1.2 hPa too high (just an example as I don't know yet how much you will be off). Then you will not touch the Relative pressure. What you have to do for this last step is to add or remove from the Absolute to affect that amount of change in the Relative pressure. Because we want to maintain the 28.0 hPa offset....so we can never ever touch Relative pressure directly. You must calibrate to the METAR only using the Absolute pressure now that the offset is set.
The bottom line is that CWOP uses your Absolute pressure and that with your elevation is used to calculate Altimeter pressure. This is something that the 3rd party AmbientCWOP site software does and that is what it sends to CWOP.
That concludes Step 2....which is to only touch Absolute pressure to cause the Relative Pressure to move by that amount until Relative Pressure matches the METAR.
When all this is said and done you can keep using the hPa units....or switch back to inHg if you prefer....it won't mess anything up. The biggest reasons for having done all the calibration steps with metric is because of a few reasons; the console internally natively is using metric (less conversions the better), the online calculators are metric, and most importantly the console's precision is more when using metric because you can adjust barometric pressure by 0.1 hPa which is 0.003 inHg and that is a level of precision that you can not adjust when using inHg....as using inHg during calibration only lets you go up or down by 0.01 inHg. Which means that using inHg if you go ±0.01 inHg then you are not being as precise as you could be....which makes it so that at times you could be off by a full 0.01 inHg due to conversion rounding. The console will track barometric pressure much nicer if you calibrate using the higher precision of hPa. This doesn't mean that hPa is better in every case for everyone. If our consoles allowed you to calibrate to 3 decimal places with inHg then that would have more precision. Some people will say that it doesn't matter because of the accuracy error limitations of the sensor....but in my experience the accuracy of the sensors is understated and for all the other reasons it is better to use the internal units for calibration because regardless error is introduced every time you convert units....so limit the number of conversions.