====== Example Program: Continuous High Speed Scanned Data Logged to CSV File ====== Here's an example app that logs software polled data to a csv file. Using the MCC 118, the data is collected using a_in_scan() in background continuous modes and demonstrates writing data in Python in blocks. The file name is auto generated based on date and time for example: yyyy_Month_dd_hhmmss.csv The data is stored in $ /home/pi/Documents/Measurement_Computing/log_files #!/usr/bin/env python # -*- coding: utf-8 -*- from __future__ import print_function from sys import stdout from time import sleep from daqhats import mcc118, OptionFlags, HatIDs, HatError from daqhats_utils import select_hat_device, enum_mask_to_string, \ chan_list_to_mask from datetime import datetime, timedelta import os import csv #this is the import to make csv file creation simple. import errno READ_ALL_AVAILABLE = -1 CURSOR_BACK_2 = '\x1b[2D' ERASE_TO_END_OF_LINE = '\x1b[0K' def main(): """ This function is executed automatically when the module is run directly. """ # Store the channels in a list and convert the list to a channel mask that # can be passed as a parameter to the MCC 118 functions. channels = [0, 1, 2, 3] channel_mask = chan_list_to_mask(channels) num_channels = len(channels) samples_per_channel = 0 options = OptionFlags.CONTINUOUS scan_rate = 1000.0 try: # Select an MCC 118 HAT device to use. address = select_hat_device(HatIDs.MCC_118) hat = mcc118(address) print('\nSelected MCC 118 HAT device at address', address) actual_scan_rate = hat.a_in_scan_actual_rate(num_channels, scan_rate) print('\nMCC 118 continuous scan example') print(' Functions demonstrated:') print(' mcc118.a_in_scan_start') print(' mcc118.a_in_scan_read') print(' mcc118.a_in_scan_stop') print(' Channels: ', end='') print(', '.join([str(chan) for chan in channels])) print(' Requested scan rate: ', scan_rate) print(' Actual scan rate: ', actual_scan_rate) print(' Options: ', enum_mask_to_string(OptionFlags, options)) try: input('\nPress ENTER to continue ...') except (NameError, SyntaxError): pass # Configure and start the scan. # Since the continuous option is being used, the samples_per_channel # parameter is ignored if the value is less than the default internal # buffer size (10000 * num_channels in this case). If a larger internal # buffer size is desired, set the value of this parameter accordingly. hat.a_in_scan_start(channel_mask, samples_per_channel, scan_rate, options) print('Starting scan ... Press Ctrl-C to stop\n') # Display the header row for the data table. print('Samples Read Scan Count', end='') for chan, item in enumerate(channels): print(' Channel ', item, sep='', end='') print('') try: read_and_display_data(hat, num_channels) except KeyboardInterrupt: # Clear the '^C' from the display. print(CURSOR_BACK_2, ERASE_TO_END_OF_LINE, '\n') except (HatError, ValueError) as err: print('\n', err) def read_and_display_data(hat, num_channels): """ Reads data from the specified channels on the specified DAQ HAT devices, updates the data on the terminal display and writes the data to a .csv file. The reads are executed in a loop that continues until the user stops the scan or an overrun error is detected. Args: hat (mcc118): The mcc118 HAT device object. num_channels (int): The number of channels to display. Returns: None """ total_samples_read = 0 read_request_size = READ_ALL_AVAILABLE basepath = '/home/pi/Documents/Measurement_Computing' mypath = basepath + '/Scanning_log_files' # When doing a continuous scan, the timeout value will be ignored in the # call to a_in_scan_read because we will be requesting that all available # samples (up to the default buffer size) be returned. timeout = 5.0 # Read all of the available samples (up to the size of the read_buffer which # is specified by the user_buffer_size). Since the read_request_size is set # to -1 (READ_ALL_AVAILABLE), this function returns immediately with # whatever samples are available (up to user_buffer_size) and the timeout # parameter is ignored. #============================================================================= # If the scan starts, create a file name based upon current date and time. # Generate the full path # to where to write the collected data as a .csv file. Open the file # begin writing the data to the file. When done, close the file. try: if os.path.exists(basepath): if not (os.path.exists(mypath)): os.mkdir(mypath) else: os.mkdir(basepath) os.chdir(basepath) os.mkdir(mypath) except OSError as exc: raise os.chdir(mypath) fileDateTime = datetime.strftime(datetime.now(), "%Y_%B_%d_%H%M%S") fileDateTime = mypath + "/" + fileDateTime + ".csv" csvfile = open(fileDateTime, "w+") csvwriter = csv.writer(csvfile) while True: read_result = hat.a_in_scan_read(read_request_size, timeout) # Check for an overrun error if read_result.hardware_overrun: print('\n\nHardware overrun\n') break elif read_result.buffer_overrun: print('\n\nBuffer overrun\n') break samples_read_per_channel = int(len(read_result.data) / num_channels) total_samples_read += samples_read_per_channel totalSamples = len(read_result.data) print("\r MyTotalSamples = %d\n" % totalSamples) # Display the last sample for each channel. print('\r{:12}'.format(samples_read_per_channel), ' {:12} '.format(total_samples_read), end='') if samples_read_per_channel > 0: index = samples_read_per_channel * num_channels - num_channels print("\r Index = %d\n" % index) new_index = 0 myArray=[] #create an empty array for i in range(0, totalSamples, num_channels): myArray.append([]) #add a row to the array (COLUMN) for j in range(num_channels): print('{:10.5f}'.format(read_result.data[j]), 'V ', end='') #append a num_channels of data to the array (ROW) myArray[new_index].append(read_result.data[i + j]) new_index+=1 print("\r") csvwriter.writerows(myArray) #Write the array to file csvfile.flush sleep(0.1) print('\n') csvfile.close() if __name__ == '__main__': main() **Attachments**\\ [[ https://files.digilent.com/reference-attachments/continuous_scan_to_csv.py | continuous_scan_to_csv.py]]