[OpenTRV-dev] python opentrv to emoncms script...

[Bo Herrmannsen]

now the script is:

import sys
import serial
import json

port = "/dev/ttyUSB0"
baud = 4800

ser = serial.Serial()
ser.port = port
ser.baudrate = baud

try:
   ser.open()
except:
   sys.stderr.write("Error opening serial port %s\n" % (ser.portstr) )
   sys.exit(1)

ser.setRtsCts(0)

while 1:
   # Read from serial port, blocking
   data = ser.read(1)

   # If there is more than 1 byte, read the rest
   n = ser.inWaiting()
   if n:
       data = data + ser.read(n)



   sys.stdout.write(data)

   if data.startswith('{'):

    j = json.loads(data)
    print j['@']



my logic is to print what comes in from serial and that part works fine

i then want to build on it and if we have a json string then write just the
units id...

the last part is failing me.. i get:


{"@":"151f","+":4,"T|C16":336,"O":1,"vac|h":94,"v|%":0}
{Traceback (most recent call last):
  File "opentrvimport.py", line 35, in <module>
    j = json.loads(data)
  File "/usr/lib/python2.7/json/__init__.py", line 326, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 365, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python2.7/json/decoder.py", line 381, in raw_decode
    obj, end = self.scan_once(s, idx)
ValueError: Expecting object: line 1 column 0 (char 0)


2015-10-06 17:05 GMT+02:00 Bo Herrmannsen <bo.herrmannsen at gmail.com>:

> Hi
>
> I started on a script that can read serial data from a rev2 unit and send
> the data on to emoncms.
>
> i get this on the serial line
>
> {"@":"2800","+":4,"T|C16":544,"vC|%":2340,"O":1}
>
>
> and so far i have this python script
>
>
> import serial
> import io
> import time
> ser = serial.Serial('/dev/ttyUSB0',4800)
>
>
> sio = io.TextIOWrapper(io.BufferedRWPair(ser, ser, 1),
> encoding='ascii',newline='\r\n')
>
> while ser.isOpen():
>
>           datastring = sio.readline()
>
> print datastring
>
>
>
>
> the serial data end with CRLF
>
> but it does not print anything.... where am i wrong?
>
> before i used this script:
>
> import serial
> import time
> s = serial.Serial('/dev/ttyUSB0',4800)
>
> while 1:
>    if s.inWaiting():
>       val = s.read(s.inWaiting())
>       print val
>
> but then i got:
>
> {"@":"0950","
> +":
> 5,"
> t
> T|C
> ":
> 1
> 9,"
> vC|%
> ":
> 20
> 0,"
> T|
> C
> 1
> 6":
> 33
> 1}
>
>
>
>
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