Starting time at X-axis not changing with time

[Omar-Abdelhameed]

Hello, I have question regarding x-axis auto scaling. I need my x-axis to save everything during my test, I tried many things like auto scale, non auto scale, x-scale editable, x-scale loose fit but still the starting point of the test is changing with time. please see picture for something similar to what I need to get and thank you. 

[GerdW · Accepted solution]

Hi Omar,

---

@Omar-Abdelhameed wrote:

I have question regarding x-axis auto scaling.

---

Your question is NOT about "x axis auto-scaling", it's about the amount of data to be presented in your chart!

---

@Omar-Abdelhameed wrote:

 I need my x-axis to save everything during my test,

---

The x axis does NOT "save" everything, it just indicates the range of data you present in the plot(s)…

---

@Omar-Abdelhameed wrote:

I tried many things like auto scale, non auto scale, x-scale editable, x-scale loose fit but still the starting point of the test is changing with time. 

---

Did you change the chart history length?

There are differences between charts and graphs in LabVIEW: charts have a history buffer, graphs don't have it.

As the history is limited in length the x axis can only show a limited range of data. As soon as older data are removed from the history buffer the x axis will start to change its start value…

Suggestion: use a graph and keep your own data buffer. Learn about decimating data before plotting them as it DOESN'T make sense to plot a lot more samples then the width of the graph in pixels…

[Omar-Abdelhameed]

Thanks for your response. yes, I need to change the data presented on the chart. I didn't mean save, I meant indicates the data only. How can I change the chart history length to be at maximum ? 

[Omar-Abdelhameed]

Thank you, I done it changing chart history from properties. 

[GerdW · Accepted solution]

Hi Omar,

---

@Omar-Abdelhameed wrote:

How can I change the chart history length to be at maximum ? 

---

Be careful with setting the chart history length to "maximum": you can easily crash your VI by doing so.

Generic advice: use a SCC tool to keep a revision history of your code…

[Omar-Abdelhameed]

Thank you GerdW. 

[Omar-Abdelhameed]

I VI crashed but it's okay since I have a copy of it. I am using LabVIEW 2024 32 bit and am not able to make the chart history length bigger than 1024 and if I try that, the VI crash. How I can increase it without any crash? 

[GerdW]

Hi Omar,

---

@Omar-Abdelhameed wrote:

 am not able to make the chart history length bigger than 1024 and if I try that, the VI crash. How I can increase it without any crash? 

---

Using a history buffer of 1024 elements usually is no problem - unless you stuff larger waveforms into each element.

Using the DDT datatype isn't helpful, too…

Replace that MergeSignal node by a simple Bundle cluster node!

I repeat my suggestion:

• Use your own data buffer (aka shift register!) to hold data.
• Decimate data before plotting in a graph. It still doesn't make sense to plot more than 1024 samples (per plot) on a graph with only ~500 width…