The modifications are now up and running, and I took the opportunity
(uneventfully!) to reinstall weewx to run under Python3, since all my other
scripts use this Python version. The service code is below. It is modeled
on 'p q's code from the hackaday article, with a number of modifications.
The only change required for Python3 was a minor modification to the Try
Except syntax. Most of the modifications to the Loop packet service were to
reduce the load on the system for something that (for the Vantage Pro 2
driver) gets called once every couple of seconds or so. The service only
actually reads the external data every minute or so, returning saved values
for the intervening calls.
import syslog
import weewx
import time
import os
from weewx.wxengine import StdService
class ArchTHService(StdService):
def __init__(self, engine, config_dict):
super(ArchTHService, self).__init__(engine, config_dict)
d = config_dict.get('ArchTHService', {})
self.filename = d.get('filename', '/var/tmp/THNow.txt')
syslog.syslog(syslog.LOG_INFO, "ArchTH: using %s" % self.filename)
self.bind(weewx.NEW_ARCHIVE_RECORD, self.read_file)
def read_file(self, event):
# save the console values in 'extra' slots
event.record['extraTemp1'] = event.record['inTemp']
event.record['extraHumid1'] = event.record['inHumidity']
try:
#skip it if it's stale. Console values will be used instead
if time.time() - os.path.getmtime("/var/tmp/THNow.txt") < 600: #10
minutes
with open(self.filename) as f:
line = f.read() # contains temp & humidity,
comma-separated
values=line.split(',')
syslog.syslog(syslog.LOG_DEBUG, "ArchTH: found value of %s"
% line)
event.record['inTemp'] = float(values[0])
event.record['inHumidity'] = float(values[1])
except Exception as e:
syslog.syslog(syslog.LOG_ERR, "ArchTH: cannot interpret value:
%s" % e)
class LoopTHService(StdService):
loopcount= 0
lastT = 0
lastH =0
def __init__(self, engine, config_dict):
super(LoopTHService, self).__init__(engine, config_dict)
d = config_dict.get('LoopTHService', {})
self.filename = d.get('filename', '/var/tmp/THNow.txt')
syslog.syslog(syslog.LOG_INFO, "LoopTH: using %s" % self.filename)
self.bind(weewx.NEW_LOOP_PACKET, self.read_file)
def read_file(self, event):
if self.loopcount == 0:
try:
#skip it if it's stale. Vantage Console values will be used
instead
if time.time() - os.path.getmtime("/var/tmp/THNow.txt") <
300: #5 minutes
with open(self.filename) as f:
line = f.read() # contains temp & humidity,
comma-separated
values=line.split(',')
syslog.syslog(syslog.LOG_DEBUG, "LoopTH: found value of
%s" % line)
event.packet['inTemp'] = float(values[0])
event.packet['inHumidity'] = float(values[1])
self.lastT=float(values[0])
self.lastH=float(values[1])
self.loopcount += 1
except Exception as e:
syslog.syslog(syslog.LOG_ERR, "LoopTH: cannot interpret
value: %s" % e)
else:
self.loopcount += 1
if self.loopcount >= 30:
self.loopcount = 0
event.packet['inTemp'] = self.lastT
event.packet['inHumidity'] = self.lastH
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