Sending a Raspberry Pi Datastream to xively

Question

I have my rpi connected up to a digital scales via RS232, a MAX3232 serial port / ttl module connected into the GPIO. Successfully collected the weight data streaming from the scales using this code (data is in blocks of 20 and the weight is at 11 - 14). This prints it out locally in terminal:

import serial
import time

ser = serial.Serial("/dev/ttyAMA0")
read = ser.read(20)

def get_num(read):
    return float(''.join(ele for ele in read if ele.isdigit() or ele == '.'))

while True:
    print(get_num(read))
    time.sleep(2)

This works great but my python code to send datastream to xively isn't so good.

def get_num(read):
    return float(''.join(ele for ele in read if ele.isdigit() or ele == '.'))

# function to return a datastream object. This either creates a new datastream,
# or returns an existing one
def get_datastream(feed):
    try:
        datastream = feed.datastreams.get("(get_num(read))")
        return datastream
    except:
        datastream = feed.datastreams.create("(get_num(read))", tags = "weight")
        return datastream
def run():
    feed = api.feeds.get(FEED_ID)
    datastream = get_datastream(feed)
    datastream.max_value = None
    datastream.min_value = None

    while True:
        weight = get_num(read)
        datastream.current_value = weight
        datastream.at = datetime.datetime.utcnow()
        try:
            datastream.update()
        except requests.HTTPError as e:
            print "HTTPError({0}): {1}".format(e.errno, e.strerror)

        time.sleep(5)

run()

It checks out OK in IDLE - but when run it generates an error as follows:

Traceback (most recent call last):
File "xivelycodescales.py", line 51, in <module>
run()
File "xivelycodescales.py", line 36, in run
datastream = get_datastream(feed)
File "xivelycodescales.py", line 32, in get_datastream
datastream = feed.datastreams.create("(get_num(read))")
File "/usr/local/lib/python2.7/dist-packages/xively/managers.py", line 416, in create
response.raise_for_status()
File "/usr/local/lib/python2.7/dist-packages/requests/models.py", line 773, in     raise_for_status
raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 422 Client Error:

I can see what the error type is - and had good help at the RPI forums. But can't figure out where I've gone wrong

Many thanks

Sending a Raspberry Pi Datastream to xively

0 Answers0