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Newsgroups: comp.soft-sys.matlab
Subject: Re: Failure to read serial port after ~5000 asynch reads
Date: Tue, 2 Dec 2008 23:20:18 +0000 (UTC)
Organization: University of Newcastle upon Tyne
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Scott,

I have experienced the same serial port problem. I have a DSP board taking to the PC using Matlab serial port. My m-file contains a repeating while loop which includes a pause(0.1) to set repetition rate. After starting it appears to run perfectly for a few thousand loops then fails. The number of loops before failure is variable. As you found, the only way to fix is to restart Matlab.  I was originally using R2007b but found it does exactly the same with R2008b.  One observation in my case was that if I only transmit data from PC to the  DSP board then it doesn't fail. So the problem appears to be associated with data coming into Matlab.

Dave


"Trent Jarvi" <tjarvi@mathworks.com> wrote in message <gc5lra$2en$1@fred.mathworks.com>...
> 
> "Scott Burnside" <no@spam.com> wrote in message 
> news:gc3a48$bjs$1@fred.mathworks.com...
> > "Scott Burnside" <no@spam.com> wrote in message 
> > <gc1479$or1$1@fred.mathworks.com>...
> >> "Trent Jarvi" <tjarvi?hox
.?%wrote in message 
> >> <gc0tco$6v3$1@fred.mathworks.com>...
> >> >
> >> > "Scott Burnside" <no@spam.com> wrote in message
> >> > news:gbub92$9sr$1@fred.mathworks.com...
> >> > > Running R2007a on WinXP with Instrument Control Toolbox 2.4.2 I am
> >> > > encountering serial port read failures after approx. 5000 read 
> >> > > operations
> >> > > connected to a TrueTime XL-DC GPS Time and Frequency Reciever.
> >> > >
> >> > > I've used continuous asynchronous, manual asynchronous (with 
> >> > > readasync).
> >> > > I've tried flow control. All methods manifest the same problem, there 
> >> > > is
> >> > > no output after about 5000 reads. It looks like Matlab's interface to 
> >> > > the
> >> > > UART driver is locking up. Serialbreak doesn't work.
> >> > >
> >> > > Nothing short of closing MATLAB and starting a new instance will 
> >> > > clear
> >> > > this up.
> >> > >
> >> > > Is this a known problem with 2007a? I find hints of this in the 
> >> > > support
> >> > > literature but I would like to be more certain before I spend the 
> >> > > money to
> >> > > upgrade.
> >> > >
> >> >
> >> > Hi Scott
> >> >
> >> > AFIAK, this is not a known problem in 2007a.  It may be a manifestation 
> >> > of
> >> > something else.   Do you have minimal example code that can reproduced 
> >> > the
> >> > problem?
> >> >
> >>
> >> Trent thanks for replying. I've gotten a trial version of 2008a and am 
> >> testing with that overnight. Right away it started out by droping every 
> >> other read operation so its clear I had to much going on in the loop 
> >> between reads and the 2007a serial interface was trying to cope 
> >> unsucsessfully. The 2008a serial interface seems more robust but I won't 
> >> know for sure until I see this run overnight.
> >>
> >> If I continue to have problems I will post some representative code. 
> >> Thanks again for your help.
> >>
> >> Scott
> >
> > Ok this is worked for about 10-hours total now using R2008a. The thing is 
> > that I'm not sure if it 2008a that fixed that problem or the fact that I 
> > trimmed alot of the bloated code in the read loop. I guess I should go 
> > back and test against R2007a again just to be sure. I'll post back with 
> > that result.
> >
> > The program reads Agilent N9020a Spectrum Analyzer marker peak search 
> > frequency and amplitutde at 10 samples-per-second over Ethernet. The data 
> > are time tagged with UTC 1-pulse-per-second time stamps taken over the 
> > serial port from a TruTime XL-DC GPS/Rubidium Time Standard. The 
> > intersecond tics are derived from the internal high resolution counter. 
> > I'm using a mex file for that (hat.mexw32 from the FEX). The resulting 
> > timestamps are accurate to within 2 ms of absolute UTC time. I'll likely 
> > post this code to the FEX after some refinement and much more testing.
> >
> 
> Hi Scott,
> 
> It may be changes we put in for the GPIB and VISA and or TCPIP interfaces 
> that also improved Serial.  I didn't find a bug report for your exact 
> problem.
> 
> Neat application.  I'd be interested in seeing it when you are ready. 
> Perhaps the upcomming LXI class B compliant machines (including Agilent SAs) 
> would be useful in this application. 
>