StdCalibrate from different sources

[Norbert F]

Hello
I am using weewx feeded from two different mqtt sources (mqtt-subscribe), is there a way to use StdCalibrate to calulate from different sources.

Example:
source1 feeds: outTemp, outHumidity.......
source2 feeds: barometer, windSpeed, rain......

If i try

[StdCalibrate]
[[Corrections]]
outTemp = outTemp / outHumidity

this is working, but when i use values from different sources like

[StdCalibrate]
[[Corrections]]
outTemp = outTemp / barometer

nothing is calculated. ( This formulas are only silly examples )

Thanks for help.

[Tom Keffer]

I think you've fallen into a corner case.

All variables referenced in a [[Corrections]] must be in the same packet or record. So, if the two MQTT feeds are creating separate LOOP packets, then any correction won't have all the variables it needs and will fail.

However, archive records are different. By then, the two streams should have been combined into a single archive record (by the accumulators). However, the engine figures that the corrections were already applied in the LOOP packets, so it does not apply them again. So, the correction is never tried.

To do what you want to do you'll have to write a service that looks for new archive record events and applies the calculation there. It would be quite simple. Using your silly example, it would look something like this (NOT TESTED):

# File user/mqttfix.py:

import weewx
from weewx.engine import StdService

class MQTTFix(StdService):
    def __init__(self, engine, config_dict):
        super(MQTTFix, self).__init__(engine, config_dict)

        self.bind(weewx.NEW_ARCHIVE_RECORD, self.new_archive_record)

    def new_archive_record(self, event):

        # The record may not have 'outTemp' and 'barometer', so be prepared for a key error exception
        try:
            event.record['outTemp'] = event.record['outTemp'] / event.record['barometer']
        except KeyError:
            pass

Then you add user.mqttfix.MQTTFix to the end of process_services in weewx.conf

-tk

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[Norbert F]

Hello

When i try this python script weewx stops with this error:

Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: Caught unrecoverable exception:
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** invalid character in identifier (mqttfix.py, line 7)
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** Traceback (most recent call last):
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** File "/home/weewx/bin/weewxd", line 148, in main
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** engine = weewx.engine.StdEngine(config_dict)
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** File "/home/weewx/bin/weewx/engine.py", line 75, in __init__
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** self.loadServices(config_dict)
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** File "/home/weewx/bin/weewx/engine.py", line 138, in loadServices
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** obj = weeutil.weeutil.get_object(svc)(self,config_dict)
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** File "/home/weewx/bin/weeutil/weeutil.py", line 1093, in get_object
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** mod = __import__(module)
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** File "/home/weewx/bin/user/mqttfix.py", line 7
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** def __init__(self, engine, config_dict):
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** ^
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** SyntaxError: invalid character in identifier
Jul 27 14:49:32 a7home weewxd[6134]: weewx[6134] CRITICAL __main__: **** Exiting.