Author Topic: Can't get my latency setting low enough...windows xp  (Read 3461 times)

Offline hardmonkeys

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Yeh, attempting to do this. Khare off of here showed how its done, made it look easy lol...

Anyway, I got my lead, installed it all, now I'm testing the port! Mines com1


I get

Port status:OK
Interface: Found!
Type: serial Pass-through
Opto/Iso: Yes
Ross-Tech design: no

Latency Test:Poor
7.9 10.9 11.9(ms)

Tried changing settings as explained here...no luck....any ideas???

Thanks
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Offline itavaltalainen

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Re: Can't get my latency setting low enough...windows xp
« Reply #1 on: 27 March 2013, 20:45 »
ok, and why can't you get latency low enough??

does it not communicate?

what cable are you using, which pc, which vcds version, windows version (SP etc)?
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Offline hardmonkeys

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Re: Can't get my latency setting low enough...windows xp
« Reply #2 on: 28 March 2013, 01:44 »
Using a eBay special lol(worked with someone else's so thought what the heck) windows xp on a asus netbook(not the greatest I admit). It recognises something is there, but when I do the full autoscan it doesn't want to communicate! I've tried changing com ports, changing USB slots!

When Khare off here done the scan using his lead, we were using my laptop, vista, alot better laptop...but the mains connection AND battery are foo'd...so I have to hold the lead in the back at a jaunty angle if I let go...the power cuts!

Will have another go over the long weekend!
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Offline Khare

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Re: Can't get my latency setting low enough...windows xp
« Reply #3 on: 28 March 2013, 11:59 »
I had no problems with the latency mate, no sure how it even affects the scanning if I'm honest. On mine as you saw as long as it says
Port status:OK
Interface: Found!
Type: serial Pass-through
Opto/Iso: Yes
Ross-Tech design: no

Then it should work  :undecided:

Offline itavaltalainen

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Re: Can't get my latency setting low enough...windows xp
« Reply #4 on: 28 March 2013, 13:11 »
The latency is the delay of the signal in layman's terms. If it is too big (and in particular if it is not consistently the same) then the car controller might not know what to do with the signal.....
The cable will send a signal but it is later than the ECU (or whatever control unit) expects it to be there (it "checks" the comm lines every so often, which is determined by an internal oscillator in the ECU).

There are a few tricks to reduce latency in these ebay cables, mostly this has to do with reducing the CPU load. I.e. close all programs you don't need, disable antivirus and so forth, I would also suggest to disable Bluetooth and Wifi, this has helped with my latency in the past.

The bottleneck (and what is causing your problem) is the USB port - it is just not real time capable....
This is true in particular for the cheap ebay bangers... they often have forged FDTI chips in the with a cracked driver which does not work well....

but would try to reduce latency in device manager to absolute minimum and buffer size to a few k....
and close whatever program you don't need (basically all but the drivers and vcds)....
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Offline hardmonkeys

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Re: Can't get my latency setting low enough...windows xp
« Reply #5 on: 28 March 2013, 16:19 »
Got a new charger for my 'better' laptop...installed it all...works perfect!!!

Thanks guys!!

'05 VW Golf Mk V GT TDI Laser Blue
'98 VW Golf Mk IV GTi Black
'97 VW Golf Mk III GTi
'58 VW Golf Mk V GT Sport TDI Steel Grey
'10 Audi A4 B8 SE Multitronic


'00 VW Golf Mk III.V Cabrio


MK3.5 Cabrio 2.0 8v Automatic to 2.0 16v Manual Conversion Project

http://www.golfgtiforum.co.uk/index.php?topic=272728.

www.dorsetautorestore.co.uk