There is no RS-485 protocol, per se. RS-485 is a hardware and signal specification. Data content is up to the user to define. The generic protocol by convention is 1 start bit, some number of data bits, maybe a parity bit and 1 or 2 stop bits.
Exact quantities are user and installation dependent, UNLESS, it's mimicing a serial UART, in which case, it's generally 1 start, 8 data, 1 stop. TTFN