REQ:linux programming to control serial port's DTR as rs485

[ZeRoN]

linux rs485

I want to write a program, running under PC. linux (redhat).
to use PC.'s serial port work as RS485, use DTR to control direction.
(use 75176 or MAX485)

Could anyone show me the sample?

Should I need to modify kernel source's serial port driver?

ZeRoN

 

[greek]

linux dtr

this is the Linux serial how to

showcase.netins.net/web/tool/info/dumbterm.html

 

[ZeRoN]

dtr rs485

The link not said about, automatically control DTR as TX/RX direction.

I mean, I want DTR=ON, send a character, then DTR=OFF automatically for all character when I write to /dev/ttyS*.