Airmar Smart transducer sending bad singal

[CSYChip]

I have an Airmar D800 depth transducer which has recently stopped sending a readable signal. It was connected to a Lowrance chart plotter through the 0183 connection for several years and occasionally to a pc via an RS422 adapter. The chart plotter has been replaced with a raspberry pi and was working properly. During a recent cruise the depth stopped reading. I am receiving ·Yww{W§è�£Ÿ§3§š£—§e§È£Ÿ§s«™wåë[uÝ}]�š£—§«‘�åë·Yww{W§è�£Ÿ§3§š£—§e§È£Ÿ§s«™wåë[uÝ}]�š£—§«‘�åë in a repeating sequence. I have tried reconnecting the chart plotter, replacing the RS422 adapter, changing the port settings. I have attempted to connect to Airmar's weather station program which has a firmware updating function but the program does not recognize the transducer. Does anyone have any additional suggestions?