megatune on usb unstable

[Arthur]

Hi all

I've got an problem with my new laptop. I always used an old one with rs232. The battery deid so I treid my new one from work.
With an rs232 to usb converter and both devices on com 4, magatune starts and connect fine but jams often. The only way to get megatune to close is by closing the windows completely.

I checked:

bits per sec =  9600
data bits =  8
paraty = none
stop bits = none

What should the flow controll be set at?

[hilly]

Communication problems with MegaTune using USB - RS232 converters are common.

It all comes down to how the converters work due the vast speed differences between the 2 interface types.
As USB is sooo much faster, what the adapter does is store a bunch of data internally (buffer) and then transmit it all in one go either when the buffer is full or after a time out. This buffering is what is messing stuff up.

The RS232 setting you gave are right and flow control should be set to off.

To fix the problem may needs admin right on your laptop, so as it is a work machine that may be an issue.

What you need to do is go into the device manager, select the USB com4 port, go into properties, then port settings, then Advanced, then reduce the buffer size (both if receive and transmit are listed seperately) to minimum (1msec).

This will then mean that as the ECU send or receives data it will get dealt with by the PC straight away instead of waiting for a load to get stored up then sent in one great big chunk.

Hilly

[Arthur]

oké

That makes sence. Megatune workt briefly and then jamed, so this buffering isseu seems logical. I'll try tonight. My it guy is so nice to give me admin rights for this. I work in a buiseness where the boss has a boss and his boss to, so nobody really cares what you do with your laptop 8).

[irishtwincam]

This is useful info.

Been using a NIKKO style adaptor without issue, but will reduce the buffer size to prevent any future issues.
If the menu option is present.

[Arthur]

I have the option to turn Fifo buffers off completely. Or should minimizing the buffering do the trick?