LabVIEW
Data table
Hello All,
Currently i making Lin bus sniffer.
I solved communication, so this is no the issue.
Problem is representation of collected data.
I getting data frames, with same ID several time per second.
i need table that shows in one row one ID, and only value of data package has changing.
Like in example below... (IDs are fixed 85, 03, 3C , and the byts values are changed)
Also if new ID appear, new line should be created...
VI is in attachment.
Thank you.
Hi milan,
which LabVIEW version are you using? This sounds perfect for the LV2019 feature of maps/sets…
You need to create some kind of LUT (look-up table) and store only the latest message value per message ID. With older LabVIEW versions I sue variant attributes to store such LUTs, as has been described very long ago!
Here's a simple example showing the 2019 Map datatype used to do this:
It's worth noting that here, I haven't stored any time information, and the entries displayed in the map indicator are sorted according to however LabVIEW chooses to sort the key (you can't as far as I know control this).
If you wanted to store time values and sort by that, you could for example store a cluster of (time, value) in your map of (key, cluster). You'd need a specific way to display them then (perhaps in a 2D string array, or a Multicolumn Listbox, or similar). You could probably write a subVI to do this fairly easily.
Edit, for clarity, most of this example is not necessary if you have a real datasource. I put the top loop and queue in only so I could both "send" and "receive" data. The bottom loop is the one doing the collection, Map manipulation, and display.
@cbutcher wrote:If you wanted to store time values and sort by that, you could for example store a cluster of (time, value) in your map of (key, cluster). You'd need a specific way to display them then (perhaps in a 2D string array, or a Multicolumn Listbox, or similar). You could probably write a subVI to do this fairly easily.
I was curious about this, so here it is below:
Really, you have to run it for the time sorting to make much difference...
Map -> Sorted 2D array by time
"hex string" to hex string
I'd guess the last one isn't great, but it works for the setup I was testing. Basically it takes a string with values that look ok in hexadecimal representation but are a bunch of weird characters or boxes in normal display style and makes them normal characters 0-F. Someone else might give a far more effective/neat implementation (I suspect it's common enough).
Without LabVIEW 2019, you don't have access to the Sets and Maps datatypes (here a Map is used), described in the release announcement here.
As a result you could implement the same code using Variant Attributes. Elijah Kerry posted a walkthrough/guide/overview here: Using Variant Attributes for High-Performance Lookup Tables in LabVIEW.
The basic idea would be to replace the Map code in my example with a Variant on the Shift Register, and then use Set/Get Variant Attribute to store the values (message, or message+time) with a key (PID). You can also use the Get Variant Attributes with no key to get arrays of keys and values, allowing you to easily reuse the subVIs I showed above.
You can remove the "In Place Element" structure (yellow box) since you don't require it when using Variants, although you can also replace the "Map Get/Replace Value" nodes with "Variant Attribute Get/Replace" (which will, for a String key, as used here, be fairly similar).
The basic structure (not fully implemented as an example) can be seen here:
Saved to 2015 using the Code Capture Tool from LAVA
