read_single_value

[dawidce]

Hi
i cant read single value from meter.
Function read_standard_readout works but i get huge amount of data.
i would like to get only one value eq. (1.8.0)

my code:
`#!/usr/bin/python3

from iec62056_21.client import Iec6205621Client
import logging

logging.basicConfig(
level=logging.DEBUG,
format="%(asctime)s,%(msecs)d %(levelname)s: %(message)s",
datefmt="%H:%M:%S",
)

client = Iec6205621Client.with_tcp_transport(address=('192.168.200.123', 2222), device_address='035 0000101', password='00000000')
client.connect()
password_challange = client.access_programming_mode()
client.send_password('00000000') # Common standard password
data_answer = client.read_value('1.8.0')
print(data_answer)`

output:
20:30:10,157 DEBUG: Connecting to ('192.168.200.123', 2222) 20:30:10,157 INFO: Staring init sequence 20:30:10,157 INFO: Sending request message: RequestMessage(device_address='035 0000101') 20:30:10,158 DEBUG: Sent b'/?035 0000101!\r\n' over transport: TcpTransport 20:30:10,158 DEBUG: Resting for 0.25 seconds 20:30:11,294 DEBUG: Received b'/POZ4LP1-VP02.04*\r\n' over transport: TcpTransport 20:30:11,294 INFO: Received identification message: IdentificationMessage(identification='P1-VP02.04*', manufacturer='POZ', switchover_baudrate_char='4') 20:30:11,295 INFO: Sending AckOptionsSelect message: AckOptionSelectMessage(baud_char='4', mode_char='1') 20:30:11,295 DEBUG: Sent b'\x06041\r\n' over transport: TcpTransport 20:30:11,295 DEBUG: Resting for 0.25 seconds 20:30:11,546 DEBUG: Received b'\x01P0\x02(0000)\x03' over transport: TcpTransport
Traceback (most recent call last):
File "./iec_net.py", line 26, in
client.send_password('00000000') # Common standard password
File "/home/pi/.local/lib/python3.7/site-packages/iec62056_21/client.py", line 193, in send_password
data_set = messages.DataSet(value=_pw)
TypeError: init() missing 1 required positional argument: 'address'
`

[dawidce]

Or maybe it's easier to parse response from read_standard_readout function and find data ?

[Krolken]

I use different strategies depending on how much the data costs. If cost and bandwidth isn't a problem I just do standard readout since I don't have to change much afterwards. Lots of MNOs also charge you in incremental steps for each session. So if you pay at least for 1 kB for every session you might as well read all of it.
If I am able I adjust the standard readout (can be done usually by the manufacturers software), I try to do that to get the data I need.
And if I just only need the one data or data not available in standard readout I do single read.

Seems like you are using the LP-1 with Wifi? So I would just read the standard readout.
But if you have time please try out the single read to find if it works properly on the device. I am trying to find a better API to use the different password mechnisms, but it seems very device specific sometimes so it might be better handles elsewhere.

[dawidce]

im using LP-1 with Ethernet. How should i parse standard readout to get single data (1.8.0?) what kind of type is AnswerDataMessage ?

[Krolken]

Simplest thing would be to use the data property of AnswerDataMessage. The data structure of AnswerDataMessage consists if DataBlock that consists of DataLines that consists of DataSets. It is just to conform to the standard and make it easy to parse the data coming from the meter, but the interesting is the list of DataSets that actually hold the data.

data_list: List[DataSet] = answer_data_msg.data

Data sets consists of address, value and unit. See

iec62056-21/iec62056_21/messages.py

Line 43 in 09d9acf

class DataSet(Iec6205621Data):

So if you only need one element search the list for it and if you think you need more values you can for example create a mapping using dict with the address as key and then just look up by address.

[Krolken]

Closing this since it seems done. If there is anything else just open it again.