On 11/30/20, Jiri Slaby <jirislaby@xxxxxxxxxx> wrote: > The difference to other control flags is that open raises DTR/RTS in any > case (i.e. including O_NONBLOCK) Yes, this is the exact root-cause problem I am trying to fix, with Johan's help. > -- provided baud rate is set (and it is > for casual serials). That means you cannot open a port to configure it > (using e.g. setserial) without actually raising the DTR/RTS. Exactly. M~