flyfisher811:
I’d really appreciate some elaboration on how you “inverted” the signal so Arduino can use it with SoftwareSerial….I’m new to this and bought the same depth finder you used. Thanks in advance...
The data is transmitted using the RS422 differential signalling system. This gives good noise immunity when using long cable lengths.
The system uses two outputs, when one is high, the other is low, and vice versa.
The correct way to receive the signal would be to use an RS422 to TTL transceiver IC such as the MAX485.
However the OP didn't bother doing this, but merely made connections to just one of the two outputs.
In order to invert the signal, he simply connected to the other output.