Chirpstack decoder needed for S2105 sensor

I have a RAK7244 gateway running chirpstack. My S2105 has joined the network but I am unable to get a codec decoder to work for the data. I have tried the suggestion about modifying the TTN decoder for chirpstack but am unable to get it to work—no data. I am not a programmer so I am not sure what the problem may be. Can someone help and supply me with a working decoder? Thanks in advance.
Bob