How to Use PC/Laptop for Loopback
Loopback-A very old and fool proof trick in books is loopback as we discussed earlier in posts about protocol.
RS-232 and RS-422 are full duplex protocol so data and be send and receive a the same moment,
So if i can short Tx and Rx lines at any receiving end i should get back what i am sending.
This test i can use Main pilot computer in control van in which telemetry software is loaded or your personal laptop or work pc.
Personal laptop or work pc are used in case you want to check the continuity of the circuit in case pilot computer is not a part of circuit for example-Sonar running on Fiber optics is completely isolated from pilot pc so to check this circuit we need to do this test via PC.
As your PC also sends out RS-232 via USB ports or if you are lucky you will have Desktop with DB-9 connector and if not you need USB to Serial port convertor(DB-9).You can either buy it from any electronics hardware store or make one yourself if you are offshore, Just search on google how to do it.
As your PC also sends out RS-232 via USB ports or if you are lucky you will have Desktop with DB-9 connector and if not you need USB to Serial port convertor(DB-9).You can either buy it from any electronics hardware store or make one yourself if you are offshore, Just search on google how to do it.
Click on Start->All Programs -> Accessories -> Communications -> Hyper Terminal
Now when you will click on hyper terminal it will ask you to make telenet a default program for your computer,Select NO and then a box will appear asking for country code and number-click on Cancel.
Then finally a box will appear(As shown below) asking for connection name,Fill in XYZ whatever you like and click OK.
Then a new Box will appear as shown below and instead of TCP/IP select port 1from connect using Drop down menu.
Once you click ok another box will appear asking for PORT settings,In these settings the first one is selection of speed or Bits per second,You can choose according to your system Modern ROV's like SMD or Even old sea eye's mostly use speed of 115200bps,Select from the drop down menu which suits you the most.
Another parameter is Flow control at bottom,Select None from drop down menu and that's it no other option we need to change.
We are ready for test our sonar circuit.
Click OK and a new blank notepad type window will appear,Start typing any rubbish, Until and unless you short Transmit and Receive line you will not see anything on screen because in hyperterminal you can only see what you are receiving but you cannot see what you are sending.
When you will create a short between Tx and Rx on sonar plug,If your circuit is fine till that point you will should see what you are receiving and if its a open circuit in between you will have a blank screen.
You can apply this technique on any equipment as your PC serial port also gives out RS-232,Which is a full duplex protocol.
I hope this info will be useful in troubleshooting
Regards
Deepanshu Giri
Another parameter is Flow control at bottom,Select None from drop down menu and that's it no other option we need to change.
We are ready for test our sonar circuit.
Click OK and a new blank notepad type window will appear,Start typing any rubbish, Until and unless you short Transmit and Receive line you will not see anything on screen because in hyperterminal you can only see what you are receiving but you cannot see what you are sending.
When you will create a short between Tx and Rx on sonar plug,If your circuit is fine till that point you will should see what you are receiving and if its a open circuit in between you will have a blank screen.
You can apply this technique on any equipment as your PC serial port also gives out RS-232,Which is a full duplex protocol.
I hope this info will be useful in troubleshooting
Regards
Deepanshu Giri
