Consult a PAC Display question

Why can we only show the details of this yellow curve?
Did I do it wrong?
What should I do to show the detailed data of a certain point on a curve?

Sorry, there is another problem.
In a Chart of R1, which command should be used to determine whether an I/O Unit (e.g. EB1) is powered down or disconnected? Use “I/O Unit Ready?” or “Error on I/O Unit?”
Which command should be used to restore communication between R1 and EB1?

Thank you!

You see the yellow pen because that is the current selected pen.
Right click on the chart and select another pen (or turn the others off).

For I/O you should be using the supported I/O enabler chart.