@braedon-dority I would add that the Digi range of modems is extensive- with many functions. They have good “Data Sheets” on their capabilities.
What it sounds like you are asking is can two S3Bs be setup like a “wire” – a link for two S3Bs – a peer-two-peer (P2P) link.
That is “print” an ASCII serial string to an S3B over the UART and have it come out another S3B uart.
I am afraid its looking at the manual to see if this can be done for the particular model, and follow the examples they give in the manual.
Like a vehicle – for exact technical capabilities dig into the manual
I know some of the 900Mhz models I looked at could do it. However, as its wireless also look at under what conditions it might loose parts the string Good luck.