GL840_example.py

from bs4 import BeautifulSoup
from requests import get
from pandas import DataFrame
from pyvisa import ResourceManager

from time import sleep

class Graphtec:

 #-----------------------------------
 def __init__(self, address, resource_manager):
 self.address = address
 self.tcpip_gl = f"TCPIP::{self.address}::8023::SOCKET" # TCPIP adress to contact
 self.instrument = resource_manager.open_resource(self.tcpip_gl, 
 write_termination='\n', 
 read_termination='\r\n')
 self.query_id = self.get_graphtec_idn()
 self.data = [] # Holds measurement data

 #-----------------------------------
 def append_graphtec_readings(self):
 """Find all the measurements of the channels and append to self.data list"""
 # Format URL
 address_channel_data = f"http://{self.address}/digital.cgi?chgrp=13"

 # Get http response
 response = get(address_channel_data) # Get response from the channel data page

 # Create response table
 soup_object = BeautifulSoup(response.text, 'html.parser') # Create a soup object from this, which is used to create a table 
 table = soup_object.find(lambda tag: tag.name=='table') # Table with all the channels as subtables > based on the HTML table class > example: [table: [table, table, table]]
 channel_readings_html = table.findAll('table') # Tables of all the individual channels > Search for table again to get: [table, table, table], each one corresponds to one channel

 # Loop over table to yield formatted data
 channels_data = [] # Holds all the found data > in format: [('CH 1', '+ 10', 'degC'), (CH2 ....]

 for channel_read_html in channel_readings_html:
 reading_html = channel_read_html.find_all('b') # Returns a row for each measurement channel with relevant data > [<b> CH 1</b>, <b> -------</b>, <b> degC</b>]

 reading_list = [read_tag.get_text(strip=True) for read_tag in reading_html] # Strips the string of its unicode characters and puts it into a list > ['CH 1', '-------', 'degC']
 channels_data.append(reading_list)

 # Append the data to the list
 self.data.append(channels_data)

 #-----------------------------------
 def get_graphtec_idn(self):
 """SCPI command to get IDN"""
 idn = self.instrument.query("*IDN?")
 return idn

 #-----------------------------------
 def add_channel_data_to_df(self):
 """Post processing method to format self.data list into a Pandas DataFrame"""

 name_index = 0 # Format is ['CH 1', '23.56', 'degC']
 reading_index = 1 # so index 0, 1 and 2 are, respectively channel name, value reading and unit.
 unit_index = 2 

 channel_count = len(self.data[0]) # Amount of channels to loop over, might depend on Graphtec device (I have 20)
 df = DataFrame()

 # Loop over each channel
 for channel_ind in range(channel_count):

 channel_name = self.data[0][channel_ind][name_index] # get the channel name
 channel_unit = self.data[0][channel_ind][unit_index] # and unit
 column_name = f"GRPH {channel_name} [{channel_unit}]" # Format column name "GRPH CH1 [degC]"

 channel_readings = [] # Stores the channel data > [0.0, 0.1, 0.0 ....]
 
 # Loop over each row and retrieve channel data
 for row in self.data:
 channel_reading = row[channel_ind][reading_index] # Read the data of channel for this row
 
 # Value formatting
 if channel_reading == '-------' or channel_reading == '+++++++':
 channel_reading = "NaN" # NaN for false values
 else:
 channel_reading = float(channel_reading.replace(' ',''))# Float for other values, remove spaces in order to have +/- 

 channel_readings.append(channel_reading) 
 
 df[column_name] = channel_readings # Add a new column with data

 return df


if __name__ == "__main__":
 
 rm = ResourceManager() # Need a resourcemanager to communicate with Graphtec via PyVisa

 ip_graphtec = "169.254.26.184" # Can be setup on Graphtec with "Menu > I/F > IP ADDRESS" (change with buttons)
 graphtec = Graphtec(ip_graphtec, rm)# Sometimes errors arise here if you can not connect, restarting the Graphtec or doing "Menu > I/F > Apply Setting" Sometimes helps. Also, try if you can visit the ip address in browser directly.


 for i in range(10):
 graphtec.append_graphtec_readings() # Measure and append to data list
 sleep(0.2) # Reading every 0.2 seconds

 df = graphtec.add_channel_data_to_df() # Add everything to one easily accesible dataframe
 rm.close() # Not closing gives annoying error
 print(df)