More USB Problems

General Topics for configuring, operating and tuning the Megajolt. Also see the <a href="http://www.autosportlabs.net/MJLJ_V4_Operation_Guide">Operation Guide</a>

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HimyKabibble
Posts: 5
Joined: Sun Sep 16, 2007 12:14 am

More USB Problems

Post by HimyKabibble »

Just got the MJ/EDIS system running on my '64 Jaguar E-type. Fortunately, it's running pretty well on the default advance tables, as I can't really use the configurator, because the USB/serial connection keeps going out to lunch, leaving the configurator complaining "timeout reading runtime data". This happens within one or two seconds of starting the engine with the 3.2.1 software, within one or two minutes with the 3.1.2 beta 3 software. The USB/serial adaptor is a Prolific chipset. The problem is clearly on the configurator side, as once it wierds out, I have to unplug and re-plug the adaptor, or I can't get anything but "can't open port". Oddly, it seems to work OK as long as the engine isn't running. Not sure what that means....
Anyone have a quick-fix for this, other than getting another adaptor, which is not easily done where I live?
Regards,
Ray L.

HimyKabibble
Posts: 5
Joined: Sun Sep 16, 2007 12:14 am

More USB Problems

Post by HimyKabibble »

I seem to have somewhat changed the behavior. I downloaded and installed new drivers from the Prolific website. It now works better, but when I went into Runtime perspective, the advance, RPM and MAP displays stopped working. Data logging appeared to still be working. I never got the "timeout" error.
With the original drivers (which were quite old), the serial I/F itself worked quite poorly. With a loopback plug on the RS232 connector, it would drop a lot of characters if I tried to send data at full speed, even at 300 BAUD! With the new drivers, it seems to be reliable even at 115kBAUD, so at least now the adaptor seems to be working properly, and the problem seems to be in the MJ configurator software. I'll play with it more tomorrow and see if I can find out more about what's going on.
Regards,
Ray L.

brentp
Site Admin
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Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

Hi Ray,

You might find this thread interesting.
http://www.autosportlabs.org/viewtopic. ... 6&start=30

The findings suggest that the USB->Serial adapters may be susceptible to ignition noise, since it only occurred while the engine was running. For racebmw, he distanced the USB->serial adapter cord with a separate serial cable; the other could not tolerate the computer being outside of the car.

If it is indeed an interference problem it could be due to unshielded electronics inside the usb-serial adapter. Is your prolific adapter the kind that has the electronics in the business end of the serial port, which can be screwed right into the MJLJ? Or is the adapter designed with female studs requiring a serial extension cable?

Your updating of the Prolific drivers was very interesting. What's noteworthy is that with the old drivers, you could still communicate, but with the car off.

Now, you're reporting that the runtime screen freezes, but it still seems to log data. With the new drivers, what do you observe if the engine is not running?

Also try the hyperterminal debugging procedure in the troubleshooting guide with the engine running.

I would love to evaluate one of these challenging environments in person. I'd probably put a scope on different points of the system- starting first with the PIP, SAW, and RS232 lines.

finally, do you have access to a computer with a built-in serial port to test with?

Regards,
Brent Picasso
CEO and Founder, Autosport Labs
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HimyKabibble
Posts: 5
Joined: Sun Sep 16, 2007 12:14 am

Post by HimyKabibble »

Just an update for anyone else here having similar problems - I've gotten mine to work reliably, I just don't completely understand why. First, download the latest drivers for your USB cable. For the Prolific cable, go to: http://www.prolific.com.tw/eng/downloads.asp?ID=31 and click on the first link. Download the zip file, then unzip it into a folder. Uninstall any existing driver, and reboot your computer. Plug in the cable, and when it prompts you for where to get the driver from, point it to the folder where you unzipped the files. When the installer runs, select the option to re-install orupgrade the drivers. The installer software is truly awful, and the prompts are in a language that only vaguely resembles English, but it does work.
Next, get an RS-232 extender cable, and put it between the MJ and the USB/serial cable. I don't know why this helps, but it did, a lot! On mine, the newer driver got it to where it would crash after a minute or two, rather than a second or two. With the extender cable in place, it seems to work perfectly. On my first attempt, it ran for over 5 minutes without a single problem. That was the first time it ran anywhere near that long.
Regards,
Ray L.

brentp
Site Admin
Posts: 6274
Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

Hi Ray,

Thanks for the update. It seems like a good candidate for the troubleshooting guide, since others have observed this behaviour with USB-Serial adapters.

Regards,
Brent Picasso
CEO and Founder, Autosport Labs
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