It sounds like your pressure sensor is not recognized by the autopilot. Which version of ArduSub are you using? Try using the latest version. You can check if the pressure sensor is connected properly, by checking the ‘Mavlink Inspector’ from the Widgets menu in QGC. If the pressure sensor is connected and operating correctly, you should see a field called SCALED_PRESSURE2 in the mavlink inspector.
What version of ArduSub are you using? You can find out by going to the parameters page, and selecting refresh from the Tools dropdown menu. Then click the blue megaphone icon in that appears with messages.
Please copy the line that looks like this: ArduSub VX.X-xxx (abcd1234) .
Your firmware has an issue with the initialization of the pressure sensor that appeared in the master branch for a couple weeks. There have been a lot of changes in ArduSub over the last month, but now we have a stable release candidate. Please update your firmware.
When you have QGC communicating with your ROV you can use the MavLink Inspector, which is in the Widgets Tab, to view the Pixhawk parameters in real time.
If your pressure sensor is being detected by the Pixhawk firmware you should have two Scaledpressure parameters showing in the Mavlink Inspector. Scaledpressure2 is the outboard pressure sensor. If Scaledpressure2 is not visible in the Mavlink Inspector then the outboard pressure sensor is not be detected by the firmware. Note, Scaledpressure2 is farther down the list of parameters in the the MavLink Inspector and is not grouped with Scaledpressure1.
Also, be sure in the GND parameter group that the secnbaro is the primary pressure sensor and not the firstbaro.
Can you please let me know the ArduSub firmware version you are using, according to the directions I gave Ooyama above? Did you use a logic level converter when using the sensor with the Arduino, or did you connect the sensor directly to the Arduino?