Hi, Your problem is nothing to do with the WMR200 driver but rather the internal workings of the StdWXCalculate service. Since you have your hands in wxservices.py, have a look at the do_calculations() method (circa line 174), you will see that the data packet provided to StdWXCalculate is converted to US units before the calculations are done and then converted back to the archive unit system before exiting. This is what is causing your problems. WeeWX does not know how to convert a temperature difference between F and C and vice versa so your extraTemp1 field is getting a double conversion as if it was an absolute (as opposed to differential) F value. There is little you can do without further hacking of wxservices.py, you could save a copy of extraTemp1 at the start of the method before the conversion and then overwrite the incorrect value in the packet as the last thing before the method exits but that is getting messy. You are really just making yourself more of an orphan.
Unfortunately this also means that the StdCalibrate suggestion I made will also not work as StdCalibrate does its stuff before StdWXCalculate so it will suffer from the exact same problem. If you were only using the differenc in a report I wuld suggest doing the calculation with some in-line python in a template but you appear to want to plot the data, that means it must be in the archive. Gary On Saturday, 11 March 2017 07:41:57 UTC+10, Karl Grant wrote: > > I might try that, in the meantime I patch wxservices.py with > def calc_extraTemp1(self, data, data_type): > if 'inTemp' in data and 'outTemp' in data: > try: > data['extraTemp1']= round(data['inTemp'] - data['outTemp' > ],1) > except: > pass > > > I needed to use the try/except as it was crashing if there was > incorrect/null data in outTemp. This worked perfectly in 3.5, now I'm back > to having problems with F -> C conversion. My db is in MetricWX, > It appears that WeeWx is still working with degF, before conversion, > > Data InTemp OutTemp CalcDifff > ActDiff InF OutF DiffF DiffFtoC > 2017-03-08 23:31:00 22.4 9.1 -4.5 22.40 9.10 > -4.50 > 13.3 72.32 48.38 23.94 -4.47777777777778 > 2017-03-08 23:41:00 22.4 9.1 -4.5 22.40 9.10 > -4.50 > 13.3 72.32 48.38 23.94 -4.47777777777778 > 2017-03-08 23:51:01 22.4 9.1 -4.5 22.40 9.10 > -4.50 > 13.3 72.32 48.38 23.94 -4.47777777777778 > Is it anything to do with changes related to the wrm200 driver? > > On Wednesday, 8 March 2017 23:55:04 UTC, gjr80 wrote: >> >> Hi, >> >> One approach for a simple calculation like this could be to use the >> StdCalibrate service to set extraTemp1. In weewx.conf something >> like(untested): >> >> [StdCalibrate] >> [[Corrections]] >> extraTemp1 = inTemp - outTemp >> >> This will not be overwritten during upgrade and should achieve the same >> result. One thing to be aware of when using temperature differences is that >> weewx unit conversion will not work on a temperature difference. For >> example, if the driver for your station emits F and your database uses US >> units, but you try to display extraTemp1 in C it will be wrong. If you only >> display F you will be fine. >> >> Gary >> >> -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-user+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
