We just successfully completed a project where we used RTLinux with its
rt_com module to do just what you have in mind. It is working very well
and we are reliably able to control just when the RTS is pulled with quite
acceptable jitter on a 486 class machine.
Check out www.rtlinux.com
If you need further assistance don't hesitate to contact me.
At 07:48 PM 9/13/99 +0200, you wrote:
>Hi,
>In my embedded linux application I've written a modbus interface (RS485)
>
>on /dev/ttyS1 (cfmakeraw) the RTS is used to enable/disable the RS485
>driver.
>
>I use the ioctl(fd[c], TIOCMSET, &status) fucntion.to change RTS'
>
>Before sending I enable RTS, send all data, (the RS485 echo's all)
>wait until all data is received, and then disable RTS.
>
>The problem is that the RTS is sometimes dropped to slow, up to 5ms,
>witch is to long (because I get an answer from the polled device withing
>3ms)
>but sometimes also fas, lesser then 500us.
>
>What is the cause of this ?
>I work with an i386 40MHz cpu at 9600 baud
>
>[EMAIL PROTECTED]
>
>
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>
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>
>
Robert D. Findlay
Senior Software Engineer
FC software Inc.
Tel: (905)659-0512
email: [EMAIL PROTECTED] Web: www.netcom.ca/~fcsoft
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