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-   -   Serial Port Drop-Out (

J-Ro 01-27-2015 11:13 PM

Serial Port Drop-Out
Hey Guys -- I've been running my Open ReVolt for quite some time now and have got just over 5400 miles on it. Its a 144 volt system with a FB1-4001 in a 1994 Ford Ranger with (fully functional clutch) manual transmission.

The problem I've been experiencing is as soon as I apply throttle the serial port drops out and I have to either unplug my serial to USB converter or close and reopen the connection (I'm using hyper terminal).

Initially I had the serial to USB converter located right next to the motor controller inside the water resistant enclosure and ran a USB cable inside the cab. I thought maybe the USB to serial converter didn't like sitting right next to the controller so tonight I built a serial extension cable (Its a twisted pair + ground wire) and brought the USB to serial converter inside the truck. This didn't really help even a little bit. The converter is a prolific Serial to USB converter.

Any ideas on what I'm missing here? Thanks!

dirtydave 01-27-2015 11:29 PM

any more info available?

J-Ro 01-28-2015 09:28 AM

I'm not really sure what else to add other than this problem occurred with RTD explore as well (which won't install on Windows 7 for me). This and the fact that I've got to "reboot" the converter by unplugging it from USB and replugging it to get the serial port active again makes me think it's probably not software.

I was thinking there might be some EMF causing the serial bus to go wonky?

Astro 01-29-2015 02:41 AM

Maybe try looping the rx to the tx on the usb to serial converter so that what you send from hyperterminal goes out through the usb to serial converter then loops back in. That way you should be able to see if the converter is happy and test it in various locations. Put something like the qbf phrase (The quick brown fox jumped over the lazy dog's back.) in a function key to enable easy sending and checking of the data.

J-Ro 02-03-2015 08:31 PM

I was able to try the suggestion of looping the converter back on itself this evening.

When looped back the converter functions properly regardless of what I do with the throttle peddle but crashes again the moment I plug it into the serial connection of the controller.

New information that I didn't have before: I get the windows dingle when the serial communication fails as if I've removed hardware then a few moments later the complimentary dingle occurs indicating that hardware has been plugged back in.

Once motor speed returns to zero again I am able to re-open the serial port and see the data flowing from the controller.


MPaulHolmes 02-04-2015 07:14 PM

Here are some questions that come to mind:
Do you have a shielded 3 wire cable? Do you have one end of the shielded 3 wire cable with the ground wire connected to the drain wire in the shielding? How long is your cable? What sort of USB to rs232 converter do you have?

Astro 02-04-2015 11:43 PM

Another thought, is the laptop running on batteries or is it plugged into power somewhere. May be a floating earth issue where the earth connection of the controller is at a different potential to the ground of the laptop.

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