What is this red cooercion dot on the output of a tunnel

[nanocyte]

I'm getting a red triangle/dot on the output of my tunnel. What is that? The wire type is the same coming in as going out.

[Bob_Schor]

What an excellent question!  I must confess it took a bit of playing around with your code (too many wires scrunched into not enough vertical space -- try to keep "horizontal wires" running horizontally, spaced apart so you don't confuse two I32 wires running close-together-in-parallel with a 1D Array of I32.

So I'm not 100% certain how you caused this problem, but here's how to fix it.

1. Delete the input Tunnel of the Case Statement (with the "coercion dot").  This will cause the wire inside the Case statement to become a dashed line -- this is OK (for now).
2. Delete the dotted wire from the lower Shift Register to the (now-missing) input Tunnel.
3. Re-create the wire you just deleted from the Shift Register of the inner For loop to create a new Input Tunnel.
4. Wire the (inside) of this Tunnel to the dashed line inside the Case Statement.  This should fix everything.

I have no idea how you created this problem.  Just don't do it again, please.

Bob Schor

[raphschru · Accepted solution]

Hi nanocyte,

It looks like one of the inside terminals of the tunnel got corrupted for some reason.

Did you convert your VI from a previous version? If yes, from which version to which version?

You can simply delete and recreate the tunnel to make the corruption disappear.

Maybe someone from NI could give some hints about how and why this happened...

What follows is just an experiment for curiosity, this should not be done in production code!

Using VI scripting, I tried inspecting the hidden (private) property "Basic Object Flags" of the inside terminals of the tunnel.

I noticed the one with the red spot has an additional bit set. The first terminal is normal (False case), and the second terminal has the red spot (True case):

You can actually force that red spot by writing the same value to any terminal's flags:

More info on the basic object flags: https://lavag.org/topic/17043-basic-object-flags/

Regards,

Raphaël.

[nanocyte]

Interesting! So, the red dot appeared in LV2025Q3. My project is in LV2018 so it was doing some converting behind the scenes but I wasn't intentionally doing conversion.

[Darren]

That flag represents a coercion dot. The inside terminal of an input tunnel should never display a coercion dot. @nanocyte, are you saying that this VI does not display the coercion dot in 2018, but when you open the VI in 2025 it appears?

[nanocyte]

No. I created the VI using LV2025Q3 under a project saved in 2018 which I believe means there's some back and forth conversion under the hood of LV2025 which sounded possibly consistent with raphschru's question. I haven't tested it with LV2018 but I suspect the dot would still be there.

[Darren]

Thanks for the additional info. My best guess is that there's some sequence of editor actions that puts the tunnel in a bad state. If you or anybody else reading this can figure out how to reproduce those steps, I'll get a bug filed. But as it stands, there's not much we can do to figure out how the tunnel got in that bad state in the first place.