Hi Jacob, thank you for your reply. I do indeed have ArduSub running on the PixHawk 2.1, and the ArduSub logo is indeed in the upper right hand corner of my QGC (see previous photo).
Re previous post: Read data of Depth/Pressure Sensor - #4 by tciii
I verified using the QGC Inspector widget that the SCALED_PRESSUR2 and SCALED_PRESSUR items contain values, and those values appear to update about once a second. The odd thing is that both items contain the same set of values, and both items report values whether I have the PixHawk I2C connector attached or not.