[NET+OS 5.1] Problems with SIO_RTS_XMIT_ENCAPSULATION serial ioctl option

I am using SIO_RTS_XMIT_ENCAPSULATION for RS485 DE control. When I open “com/0” and set this option via ioctl() the first time after system bootup it works ok. If I then close “com/0” via close() and then open it again and set the option via ioctl() I get an EIO error. Looking into netos_serl.c, if seems to be a problem with pChan->options not beeing handled correctly if the channel is closed and then opened again. pChan->opMode is set to 0 when the channel is opened, but options is not, so the second time one does SIO_HW_OPTS_SET via ioctl() it is not performed at all. What is the best way to fix this? I am using the 06/13/03 ESUN version of netos_serl.c.