Siemens SIMATIC RF1000 Operating Instructions Manual page 36

Programming
7.2 Programming via USB/RS232 interface (using DLL functions)
Note that all the following functions, when operating via the RS232 interface, can
only be performed once a connection to the reader has been established with the
"brp_open_serial_session" function. If this is not the case, an error is signaled back.
Note
Parallel operation
Note that you can operate several RF1040R/RF1070R readers in parallel via the RS232 interface
or with the help of a COM port emulator.
Function call
int
brp_open_serial_session(
int * Handle,
int com_port,
ser_baudrate baudrate,
ser_parity parity
);
36
Operating Instructions, 05/2023, C79000-G8976-C432-10
SIMATIC RF1000