Is there a way to turn off and on trend lines while still collecting data in the chart history.

[StevejD]

I can use a relay to turn the signal off and on, but it leaves gaps in the trend line when turned back on.

[altenbach]

Replace the trend data with NaN and it will not show the on graph until the values are again normal.

Can you show is your VI or at least a picture so we can see what you are talking about, thanks!