Diagnostics and Repair - Communications

Communications problems can result in loss of control of the ROV. Communications in the Pro 4 occurs at several levels.

The computer has to communicate with the control panel via the USB cable. First verify that the cable is connected. The computer must also recognize the control panel devices, specifically the RS-485 interface. The RS-485 device will only be recognized while the control panel is turned on. To check the status of the communications with the RS-485 device, the control panel must be turned on. The RS-485 interface can be confirmed by checking the Ports in Device Manager. To access device manager, open the Windows Control Panel, and in the Classic View, click on System. Next, click on the Hardware tab, and then the Device Manager button. Click on the plus sign (+) next to Ports and confirm that the SeaLevel RS-485 port is listed as one of the ports. If the RS-485 device is not listed, unplug the USB cable, wait a few seconds and plug it back in. If the RS-485 device is still not listed, power down the control panel and reboot the computer. If the RS-485 device is not listed after a shut down, restart and reboot, a problem with the USB cable, RS-485 device, or internal USB hub or controller is possible.

The control panel must communicate with the ROV through the tether. Communications occur via pins 7 and 8. verify the continuity of the tether to ensure all conductors are intact. The tether conductors are straight through - pin 1 to pin 1, pin 2 to pin 2, etc. You can also connect the ROV directly to the control panel without the tether to either rule out or confirm whether the tether is the problem.

Test Points

Test	Procedure / Location	Expected Result
Communications device present	Verify "SeaLINK +485Isolated USB to RS-422/485 Converter (COMx)" is visible in Device Manager under "Ports"	Device recognized and no warnings
Measure tether Ohms for continuity	Tether pin 7 male to pin 7 female	Continuity
Measure tether Ohms for continuity	Tether pin 8 male pin 8 female	Continuity
Test tether for a short	Tether pin 7 male/female to any other pin	No short
Test tether for a short	Tether pin 8 male/female to any other pin	No short
Measure control panel Ohms	Control panel tether pin 7 female to control panel tether pin 8 female	120 kOhm +/-
Measure ROV Ohms	ROV tether pin 7 male to ROV tether pin 8 male	120 Ohm +/-
Measure ROV Ohms	ROV tether pin 7 male to ROV accessory port pin 7 female	120 Ohm +/-
Measure ROV Ohms	ROV tether pin 8 male to ROV accessory port pin 8 female	120 Ohm +/-
Measure ROV Ohms for continuity	ROV tether pin 7 male to ROV accessory port pin 8 female	Continuity
Measure ROV Ohms for continuity	ROV tether pin 8 male to ROV accessory port pin 7 female	Continuity