Re: Relative time in XY graph

[Bruce Hill <bhill@slac.stanford.edu>]

Hi Himanshu,
The waveform PV has a single timestamp, which generally is the
time when the array was last modified.    When you display the
waveform using EDM's xyGraph, you make the waveform be the Y PV.

If the X PV is not used, xyGraph will plot one point for each value
in your waveform array, and the X axis will just be the array index.

One option would be for you to provide a 2nd array for the X PV and
fill it with the time values for each value in your waveform.    The best
way I know how to create the time array would be with the aSub record,
but maybe other EPICS user's may have other ways to do that.

The xyGraph widget also has a Time option for the X Axis, but in my experience
this only works for scalar PV's.     With a scalar PV, each update of the PV value
also updates the timestamp, and xyGraph can show those timestamps as either
relative durations in seconds from the time the graph is opened, or as a time/date
string.

Hope this helps!
- Bruce

On 5/15/2013 1:58 AM, Himanshu Tyagi wrote:

can we do this in control system studio also?

i have another question from where does the waveform PV gets its time for plotting in XY graph?

i am plotting a PV of waveform type record but I am somehow getting the wrong time displayed in graph.

please suggest

On Wed, May 15, 2013 at 12:10 AM, Fabian S. <epics@shony.de> wrote:

at least in EDM there is a TriggerPV somewhere in the grap settings that
should do what you describe. Down side is that your graph gets updated
even if the value hasn't changed.

The trigger pv could be a calc which gets updated every 1 second and
counts up to 5 where an additonal condition stops the counter/trigger-value.

On 05/14/2013 08:56 AM, Himanshu Tyagi wrote:
> Hi,
>
> I m new to epics framework. We have a requirement for getting the relative
> time in XY graph so that the all the signals start and stop at same time
> value.
> Is there any way we can control the time values in XY graph and
> have relative scale ,i.e. time should start from t=0 to t=5 sec and then
> graph should stop.
>
> Regards,
> Himanshu
>

--

Himanshu Tyagi

Software Engineer Trainee

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Pune

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