Logging intervals/readings

[GrahamS4]

Hi,

When logging an engine block, say 003 the rpm intervals measured at vary. Not only do they vary, but the frequency of the readings seem to vary from session to session too - say one occassion I might get 7 readings between 3000 and 6800 rpm and another I might only get 5. Number not exact but you get the idea.

What effects this variation and is there anything I can do/configure to make get more readings or at least more consistant intervals etc?

I am using the non canbus USB cable with the latest release software.

thanks
Graham

[Sebastian]

Besides using turbo mode (if available), you may want to check the protocol options.

http://www.ross-tech.com/vag-com/tour/o ... creen.html

Have you tried logging just one group/block at once?

[GrahamS4]

thanks

What should I be checking in the options?

[SJS]

blk int . It looks to be setup in mSec Mine was set at 55 so i guess it takes 2 measurements every 1.1 Secs. I changed this to 30. So it should take 3 in 0.9 secs.

[GrahamS4]

Does performance of the laptop affect the sample rate or is the limiting factor the USB interface or more likely the car?

The laptop I tend to use for vagcom is an old PIII but with 1GB RAM.

Does a BlK Int rate remain constant despite the speed of the laptop used?

I presume the default value of 55 is the fastest sample rate found to be compatible with all controllers?

When logging 3 measuring block at a time, on block 003 there is about 300rpm average between the intervals. Is that good/bad/average?

[Sebastian]

Does performance of the laptop affect the sample rate or is the limiting factor the USB interface or more likely the car?

A slow laptop can indeed influence the sampe rate, while the USB port is not really the limiting factor. USB itself can be much faster than what any ECU would actually send but the conversion which is being done by the interface and the pc to use USB instead of a a serial connection takes a little bit of speed.

Does a BlK Int rate remain constant despite the speed of the laptop used?

Yes, it refers to the protocol timing between PC/VAG-COM and the car.

I presume the default value of 55 is the fastest sample rate found to be compatible with all controllers?

Correct, it's the most compatible standard setting.

When logging 3 measuring block at a time, on block 003 there is about 300rpm average between the intervals. Is that good/bad/average?

What's the actual rate you are getting? Personally my experience is that everything below 3 samples per second is questionable in terms of it's use but at the end it really depends on what and why you are logging.

[GrahamS4]

What's the actual rate you are getting? Personally my experience is that everything below 3 samples per second is questionable in terms of it's use but at the end it really depends on what and why you are logging.

Hmm, well look at this extract for example. Not sure how many blocks I was logging here, but it would have been at least two.
Looks like I am only getting two samples per second at best, more like one in places.



Do you think this is down to processor of the laptop? Like I say PIII but it does have 1GB RAM. Runs XP OK generally. Nothing excessive running in the system tray etc.

[Sebastian]

More likely to be related to the ECU, I mean 3 blocks at once is for most of the ECU's quite a mess to handle. I guess your value with just one block is 6+ and that would be normal.

[GrahamS4]

Thanks.