How do I pass data into a sub vi?

[Dave123]

Hi, I'm trying to pass an integer value into a sub vi that displays
this value on a tank indicator. I've connected the tank indicator in
the sub vi to one of the terminals but in the calling vi it seems to
see the terminal as an output not an input. I can't find any way of
selecting whether the terminal is an input or an output. How do I
change the terminal to an input?

I'm using LabView7.0 Express on a Mac.

Hope you can help.
Dave G.