topic Re: Inconsistent newline using Write to Text function in LabVIEW

Inconsistent newline using Write to Text function

_Ben_ — Mon, 31 Mar 2014 16:23:18 GMT

Hello,

I have a subvi in my project that is used to log data to a text file according to a user specified recording interval. I use the Get Date/Time in seconds function and concatenate the output to my data using format into string. Then I use the Write to Text File function to write the string to the file. 99% of the time, Write to Text seem to appends a CRLF to the end of the line. 1% of the time it doesn't seem to append a CRLF and I end up with a line in my log file that looks like "Timestamp,Data,Next_Timestamp,Next_Data"

I suspect a race condition maybe causing my trouble due to the inconsistent nature of the problem, but I don't see where it could be coming from. I've attached a .png showing my logfile code. Please let me know if you need any additional information. Thanks!

Re: Inconsistent newline using Write to Text function

crossrulz — Mon, 31 Mar 2014 17:04:46 GMT

Your issue would have to be coming from the Current Data input. So you need to look everywhere that you call this subVI and make sure the end of line constant is correct.

Re: Inconsistent newline using Write to Text function

_Ben_ — Mon, 31 Mar 2014 17:33:00 GMT

Thanks for the reply!

Unless I am somehow mistaken, I am not providing the end of line constant. Instead, the Write to Text function is appending it to the string I am passing. It's just sometimes, for whatever reason, Write to Text doesn't append the end of line.

Re: Inconsistent newline using Write to Text function

crossrulz — Mon, 31 Mar 2014 17:41:39 GMT

_Ben_ wrote:

Unless I am somehow mistaken, I am not providing the end of line constant. Instead, the Write to Text function is appending it to the string I am passing. It's just sometimes, for whatever reason, Write to Text doesn't append the end of line.

You are mistaken. The Write To Text File does not append an End Of Line. You have to write it.

Re: Inconsistent newline using Write to Text function

billko — Mon, 31 Mar 2014 17:55:03 GMT

Why don't you post the actual code instead of a picture so we can see what is in the other cases not visible in the picture? Seems kind of convoluted for simple log file.

Re: Inconsistent newline using Write to Text function

JÞB — Mon, 31 Mar 2014 18:28:29 GMT

@_Ben_ wrote:

Hello,

I have a subvi in my project that is used to log data to a text file according to a user specified recording interval. I use the Get Date/Time in seconds function and concatenate the output to my data using format into string. Then I use the Write to Text File function to write the string to the file. 99% of the time, Write to Text seem to appends a CRLF to the end of the line. 1% of the time it doesn't seem to append a CRLF and I end up with a line in my log file that looks like "Timestamp,Data,Next_Timestamp,Next_Data"

I suspect a race condition maybe causing my trouble due to the inconsistent nature of the problem, but I don't see where it could be coming from. I've attached a .png showing my logfile code. Please let me know if you need any additional information. Thanks!

just slap a build array on the string in front of the write to text file.

I know, that kind of sucks to have such a simple solution available but it works without having to go and dig through all the callers. That EOL conversion can forgive a lot of string formating mistakes.

Re: Inconsistent newline using Write to Text function

billko — Mon, 31 Mar 2014 18:34:15 GMT

@JÞB wrote:

@_Ben_ wrote:

Hello,

I have a subvi in my project that is used to log data to a text file according to a user specified recording interval. I use the Get Date/Time in seconds function and concatenate the output to my data using format into string. Then I use the Write to Text File function to write the string to the file. 99% of the time, Write to Text seem to appends a CRLF to the end of the line. 1% of the time it doesn't seem to append a CRLF and I end up with a line in my log file that looks like "Timestamp,Data,Next_Timestamp,Next_Data"

I suspect a race condition maybe causing my trouble due to the inconsistent nature of the problem, but I don't see where it could be coming from. I've attached a .png showing my logfile code. Please let me know if you need any additional information. Thanks!

just slap a build array on the string in front of the write to text file.

I know, that kind of sucks to have such a simple solution available but it works without having to go and dig through all the callers. That EOL conversion can forgive a lot of string formating mistakes.

So it won't add an extra EOL if one is already there?

Re: Inconsistent newline using Write to Text function

JÞB — Mon, 31 Mar 2014 18:45:25 GMT

@ Not so lowly minion

Nope, It'll convert any EOL it sees to the OS specific EOL and only add one if its missing one.

Open the example from the help and play with it to prove it to yourself.

Re: Inconsistent newline using Write to Text function

_Ben_ — Mon, 31 Mar 2014 19:22:08 GMT

Sorry about that! Here is the code.

Re: Inconsistent newline using Write to Text function

altenbach — Mon, 31 Mar 2014 19:29:29 GMT

This code looks very fragile.

How do expect a reasonable refnum out if the FALSE case executes?
Definitely don't convert EOL when writing (right-click...uncheck convert EOL)
What is the reason for the sequence structure? Makes no difference here.
...

Re: Inconsistent newline using Write to Text function

crossrulz — Mon, 31 Mar 2014 19:31:44 GMT

@JÞB wrote:

@ Not so lowly minion

Nope, It'll convert any EOL it sees to the OS specific EOL and only add one if its missing one.

Open the example from the help and play with it to prove it to yourself.

Guess again, Jeff.

Re: Inconsistent newline using Write to Text function

JÞB — Mon, 31 Mar 2014 19:47:28 GMT

That's not quite kosher

Re: Inconsistent newline using Write to Text function

_Ben_ — Mon, 31 Mar 2014 19:49:12 GMT

Thanks for your reply, altenbach. I will try to answer your questions, and if you have suggestions for a better way, please let me know!

The false case can only execute after the true case. The true case queries a device to obtain current channel names, which are then used as a header in the log file. The false case writes numeric data to the log file under the header.

Could you elaborate on why I should uncheck convert EOL? Is this causing the inconsistent behavior that I am seeing? If I add an end of line to my format into string function and uncheck convert EOL, do you believe that will fix the problem?

The sequence structure is leftover from some debugging I was doing and should be deleted. Thank you.