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Re: serial port response time



I've done a little narrowing down on this: getting a response from the ETRAX
devboard seems to take about 160ms.
This could be:

1) a read delay  for the ETRAX receiving the command, and a fast write
2) a fast read and a write delay
3) a read delay on the machine issuing the commands.
4) a combination of the above.

Is there away to determine where the delay is occuring? Can chaning the kernel
configuration reduce these delays?
I'd rather not write my own serial driver, but if that's what it takes I'll give
it a shot.

thanks again,

	Kevin

Kevin Wooley wrote:
> 
> I'm writing an application which listens on the serial port for a command
> from another device.  It needs to send a response to this command back over the
> serial port within 30ms of receving the command, with a 3 ms inter-character
> timeout.  I'd think that this would be fairly straight forward.  I switch on the
> command, determine response and send it back.
> 
> But this doesn't seem to work right, especially when sending more than a few
> bytes.  I want to be able to send 25-50 bytes at a time, but the receiver
> running on my host machine timesout the read before it finishes.  It seems as if
> all 25 bytes are not being sent as a continuous block, but pausing in the
> middle.
> 
> Any ideas on how I could speed things up?  This might be a deal-breaker for my
> application if I can't get it to work.
> 
> thanks,
> 
>         Kevin