How to Tell if Your Mk II Receiver is Working

This discussion is valid for a Mk II Receiver (serial or USB only). This should be the first step if you are troubleshooting a Mk II system.

To determine if the receiver is working:

1. Power up CeruleanTracker.

2. Go to the "ROVL Rx" tab of the main window.

3. Check at the bottom of the window and make a note of which active COM ports are detected.

4. Plug the receiver into the PC using a serial-to-USB cable such as the Cerulean Sonar cable you purchased with your system.

5. Waiting a few seconds, see what new active COM port appears.

You can plug and unplug the receiver as you are testing, but be aware that sometimes Windows gets confused about what COM ports are active, especially if you are plugging and unplugging multiple devices, and you may need to reboot if the active COM ports list stops updating or you cannot connect to a COM port that you know to be correct.

1. Make sure the receiver connection is set to the correct COM port. Also make sure the baud rate is set to 115200. There are only rare and obscure reasons to use another baud rate with a receiver, and none of them can be triggered accidentally. See the example below of a connection to COM port 6.

Connected to a receiver on COM port 6

1. The connection status should change to "Open" with 15 seconds of plugging in the receiver. If you use the "search for" option it may take longer to open. If the status does not change to "open" you need to resolve the problem. Possible issues: bad serial-to-USB converter, Windows is confused as noted above, bad driver (Windows comes with a suitable driver for the Cerulean cable and for the Blue Robotics BLUART), bad cable. Even if the receiver was non-functional for some reason, the connection-open status is determined by the serial-to-USB converter.

2. A few seconds (fewer than 15) after powering (plugging in) the receiver, and AFTER the connection status changes to "open", the communication status should change to "Receiving on serial" and incoming messages should be displayed below the communication status label. Generally these messages are "$USRTH" messages, and in a bench test, maybe only the last couple of characters will be changing as new messages come in. If this does not happen you need to figure out why before continuing. Most likely this will be a cabling issue.

3. If you check the "show $USRTH window" checkbox, a new window will pop up that decodes the $USRTH messages as they come in. One of the items is a count of messages received. This should be counting up at 1 Hz.

USRTH Window

1. If you check the "show command window" checkbox, a new window will pop up that will display informational messages and help with sending other commands (example below). One feature is the text window that can show progress messages as the receiver boots up. Some of the messages include dates for the firmware, model (in the case, Mk II), some of the non-volatile memory settings such as speed of sound to use), and the IMU connection.

ROVL Command Window showing a missing-GNSS error.

1. The display may also show unusual errors. Note the final two items: "GNSS module is not present", and "Autosync option is not active". This indicates either this is a very old Mk II (and there are almost none in circulation) or there is a problem with this Mk II receiver. For this specific problem you would need to contact Cerulean Sonar. Most often, the receiver will boot with no problems, as shown below. Note the last line is "Operating Channel A". When troubleshooting this should be the case. If it says something different, send a "IA" ('eye' not 'one') command by typing it into the command textbox (without the quotes) and pressing ENTER.

ROVL Command Window showing nominally no errors.

1. Go back to the Dashboard tab of the main window. It may show something like the example below. Note the "Waiting for sync" status. This indicates the receiver has not yet achieved a GPS lock since it booted. In order to finish troubleshooting the system, the receiver needs to have had a recent GPS lock.

Dashboard tab showing ROVL has not achieved GPS lock and does not have a complete IMU calibration.

1. Take the receiver to a place where it can "see" the sky (and is not submerged) and wait for it to achieve GPS lock (typically 30 to 60 seconds). When it does, the "T Since Sync" status will reset to zero. When it loses GPS lock, the time will start counting up. During troubleshooting you should let the receiver re-acquire a lock whenever the time since sync is over 30 minutes.

Dashboard tab showing ROVL has achieved GPS lock within the last second and does not have a complete IMU calibration.

1. To determine if the receiver is receiving commands, send a "?" command by typing it into the ROV Command Window command textbox (without the quotes) and pressing ENTER. You should see the text in the text display area update.