| Electronics > Repair |
| Bad RS422 signal? |
| (1/2) > >> |
| Alex_Baker:
I am attempting to read RS422 data from a Lowrance HDS9 sonar/chart plotter. It can output and recieve data through a 4-wire RS422 interface. I am having troubles reading data and decided to use an oscilloscope. The below image is what I captured by putting the scope probe on the two TX wires. I do not have much experience with RS422, but this looks bad. Can anybody confirm this suspicion? |
| hexreader:
First thing to do is change oscilloscope channel 1 coupling from AC to DC ... or use channel 2, which is already DC coupled. |
| Alex_Baker:
Dang, I can't believe I did that. Probing a "good" rs422 signal looked fine with channel 1 though, so I don't think that is necessarily the problem. Unfortunately I wont be able to do more testing until Monday, this equipment is at a school lab. |
| hexreader:
Another thing - trigger on falling edge, not rising Good luck :) |
| Alex_Baker:
--- Quote from: hexreader on August 09, 2024, 09:55:08 pm ---Another thing - trigger on falling edge, not rising Good luck :) --- End quote --- That would not change how the signal looks, would it? why would it matter? |
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