"Last Update" in the probe watch window is not proper when "Retain Wire Values" is ON and probe is attached after running the VI

[ufaruque123]

Switch on the "Retain wire Values".

Probe a wire before running the VI and it shows nothing in Last Update

Run the VI and it shows the time stamp when it was Last Updated

Now attach the probe with something which was not attached before running the VI and you will find the last value with Last Update time as current stamp.

Notice the time stamp of Probe 37. 

Delete the probe 35 and probe it again and notice the timestamp. (Note: We are not running the VI again, just deleting and adding the probe is updating the time stamp)

Why?😕

From LabVIEW help,

• Last Update
  —Displays a timestamp that shows the last time data passed through the probe.

Which is actually not the last time data was passed through the probe 37.

Either it should not show Last Update time in this case or it should show the actual time when it was updated.

Above behavior is only when "Retain wire Values" is ON on for the VI.

[RavensFan]

It seems logical to me.

The wire carries a value, not a timestamp associated with that value.

When you attach a probe, when it sees a value, then applies the current time of the PC to that value within the probe display.

So with retain wires values turned on, when you place a probe, the code behind the probe says "hey, there's a value, I'll attach the current time to it".  A probe is not smart enough, and there is no data in saved in the debug process while Retain Wire Values is on to know that the value was actually dated from seconds ago, minutes ago, or event days ago.

[ufaruque123]

That was my point. It's not smart enough.

If VI is not run after attaching the probe it should not show the timestamp. If retain value was ON it should show only the last value, not the timestamp.

What is the use of getting timestamp of probe attachment.

[RavensFan]

So how do you want it to show a value and no timestamp?  A timestamp value of 0:00:00 ?

Honestly, I've been programming LabVIEW for 15 years.  I've rarely used retain wire values.  (I should use it more, but don't think about it.)  And I've never heard anyone have an issue with the timestamps in probes before.  You are the first.

So could it and should it be improved.  Probably.  But I doubt you'll see it happen with classic LabVIEW.  I don't know how it behaves in NXG.  Now that you know there is an issue, you can keep it in mind.