FTDI USB to rs232 problems
The USB disconnect could be caused by EMC possibly from the engine.
You could try increasing the reset pipe retry count described in section 5.1of our advanced drivers application note
5.1 Adjusting the Reset Pipe Retry Count
In some rare cases, it may be necessary to increase the number of times the driver tries to reset a USB pipe on which an error has occurred, for example in noisy environments where a lot of USB errors occur.
The default value for the reset pipe request retry count is 50. This default value may be changed in the FTDIBUS.INF file by editing or including the following fragment.
In this example fragment, the reset pipe request is set to 100.
This value is held in the registry key located at
Made a rally BMW 325 install. When making the set up I had no problems but suddenly when driving Vt louse connection and says “unplug usb adapter”
Driver is updated to the lasted one http://www.ftdichip.com/Drivers/CDM/CDM20814_WHQL_Certified.zip
Using Win Xp
Wiring harness typ vems 6 cyl.
The installation is made like this http://www.vems.hu/manual/vemstune/help2/htmls/main/preferences/ecu_comm_dialog.html
Consumer installation BMW 325 turbo.
They has the same problems and we tried to help but nothing will fix the serial problem.
Can I change settings in Vt or will it help (timeout, ignored error, write delay)
It will be helpful if someone could help out on this one
Regarding settings in vemstune, as long as write delay is >25 and timeout is 100 it is not related to that.
It is most likely related to ignition noise, broken spark plug, distributor or plug wires.
- check spark plug wires
- check spark plugs
- check coil(s)
- Distributor cap, rotor etc..
- if coil on plug, check that all the rubber boots are in good condition and clean of dirt, oil or water.
- Use a serial cable extension between usb adapter and ECU (This helped in some occations)
- If using a in car 12V notebook charger, try to unplug, ground can go through the usb instead of the cig plug if the socket is bad.
Also, PC (even a desktop) with real serial port often helps.
We have 2 wireless systems working (that can soon help installers with windows-usb-driver PITA), one with Wifi router (OverTCPWireless), the other (physically smaller) with bluetooth. We're also working on zigbee.