select "field occurrence" in "Plots" window

asked 2025-12-22 12:13:21 +0000

Hello!

I am working with IEC61850 Sample Values data. Inside the frame, there is a "sv.meas_value" field in witch the measurement values are decoded. In fact, this "sv.meas_value" field is an array of values (eg. voltage/current per phase, at that the frame sample time).
What I want to plot is one of the values (eg. the first field, corresponding -eg- to phase A voltage).
It seems that there is no option in the Plots window to select a occurrence of the "Y Field", and I tried several options (use of sv.meas_value[1],sv.meas_value[1:1],sv.meas_value#1,sv.meas_value@1,...) unsuccessfully.

As comparation, when editing columns, it is posible to select the "field occurrence", and it works nicely :-)
Any help would be appreciated. And if this options is not implemented, it would be nice (and I think easy) to add it.

Thank you and regards!
Josep

(ops... I was trying to add a couple of images, but it seems that I do not have points... sorry :-) )

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An actual capture file is much easier for us to look at, you can use any public file share and post a link to it back here.

grahamb ( 2025-12-22 13:39:29 +0000 )edit

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answered 2025-12-22 15:24:12 +0000

Chuckc
3148 ●6 ●655 ●20

Current open issue: 18827: Ability to filter on occurrences of a field

(There is a sample capture attached to: 14541: sv.meas_value and sv.meas_quality in Sample Values dissector
See the comment about setting preference for sv to decode)

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Ok! Thank you for the quick answer. Regards!

jmarro ( 2025-12-22 15:59:35 +0000 )edit

You might be able to add a custom field with a Lua script then plot that.
There has been a discussion (can't find it right now) about the order that field occurrences are returned when queried in Lua. Will search more if you're interested.

Chuckc ( 2025-12-22 19:48:22 +0000 )edit

Hello. I will try to find what you comment, thank you!. My workaround was quite simple, as I commented it is indeed possible to create one new column with this field, and then just "Export packet dissections" in CSV, and then plot it with my favorite tool. But it would be nice to be able to just use the "Plots Windows" inside Wireshark (I tried, and in fact it plots the data correctly, but the problem is that it plots _all_ the array fields and the the graph is not nice).

And additional comment from my side, in fact, the open issue that you refer (18827) is indeed related with this issue, but I do not know if it is the same... that issue refers to the capability of select fields when create a filter, and my issue is about the capability of select fields in the "Plots Windows" Regards!

jmarro ( 2025-12-23 07:35:17 +0000 )edit

Please add your use-case (plotting a specific occurrence of a field) to the open issue mentioned above. It could help in getting this feature request noticed again and perhaps implemented in a way that fits your needs as well :-)

SYN-bit ( 2025-12-23 12:05:37 +0000 )edit

Sure. I'll do it as soon as possible. Also, I agree that the best solutions would be a generic one, that could be used for "Plots" (my case), but also in filters and other places where data "array-like" could be used. Regards!

jmarro ( 2025-12-23 12:12:58 +0000 )edit

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select "field occurrence" in "Plots" window

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select "field occurrence" in "Plots" window