Python Script in LabVIEW Context

[lvbms]

Hi , 

I've a python script which writes a file periodically (every 2 seconds) . When I run this python script from command prompt or using IDLE, the file is updated periodically and I can read the file. 

But when I run the same python script using  system exec VI in LabVIEW context. It doesn't update the file periodically and updates the file when it got terminated. So because of this I can't plot my data in run-time. 

Let me know if there is any other way of doing this.

[ainnrc]

Set 'Wait Until Completion' input to False.

An alternative would be to create a BAT file of your command, then call the BAT file using system exec.vi

[cbutcher]

Can you share either 

A) the Python script you're using or 

B) a similar script that uses the same method to write to file periodically (and so exhibits the same problem)?

[lvbms · Accepted solution]

Problem solved as I was not using "f.flush()" and "os.fsync(f.fileno())". After adding this I was able to resolve the issue I was facing. It was not a issue with System Exec. Now I can read the file and plot the data as I need. Thanks for pointing out "Wait untill Completion". I need to set it to false because I want to let the script run and don't want to wait for its completion.

def write_csv(*args):
my_str= str(args[1]) + "," + ",".join(args[2]) + "\n"
#print (my_str)
file_handle = args[0]
file_handle.write(my_str)
file_handle.flush()
os.fsync(file_handle.fileno())