"Too many communication errors" connecting to HVAC on A4

ImpellerCDN · 05-25-2006, 11:55 PM

I can rarely connect to the HVAC controller on both my B5 A4 and S4. Typically I time out with a "too many errors..." message.

3rd party cable (usb). vag-com 409.11.

Any wisdom out there? STFA but no answers...

Many thanks.

Theresias · 05-26-2006, 04:38 AM

Uwe@Ross-Tech.com · 05-26-2006, 05:40 AM

and 3rd party USB interfaces are quite poor at maintaining precise timing because they emulate a serial port and this emulation tends to slow things down.

-Uwe-

ImpellerCDN · 05-26-2006, 11:15 AM

...which ups the clockrate by 2x. Since you mention,

>>>emulation tends to slow things down

it might help with the com timing precision.

Let you know.

Cheers.

ImpellerCDN · 05-26-2006, 09:21 PM

From 16ms to 12ms. HVAC now responds on both my B5 cars. Other controllers seem happy too.

Cheers

Bracketracer · 05-27-2006, 09:03 AM

I've got the real thing (Hex-USB with 512.4), and have a LOT of problems connecting, or maintaining a solid connection with HVAC controllers in late '90s and early '00s cars. Flaky enough that I can rarely perform basic settings.

Uwe@Ross-Tech.com · 05-27-2006, 10:00 AM

But the HEX-USB should be able to do it without any problem, *if* there's no other issues with the PC.

What kind of PC? What version of Windows? Have you been to the link below?

-Uwe-

http://www.ross-tech.com/vag-com/faq_2.html#2.5

nasdaqer · 05-29-2006, 12:29 PM

I am having the same problem

thanks

Maini · 08-19-2008, 07:03 PM

http://forums.audiworld.com/vag/msgs/16474.phtml

05-25-2006, 11:55 PM	#1
ImpellerCDN New Member Account #: 61441 Join Date: Aug 2003 Posts: 23	"Too many communication errors" connecting to HVAC on A4 I can rarely connect to the HVAC controller on both my B5 A4 and S4. Typically I time out with a "too many errors..." message. 3rd party cable (usb). vag-com 409.11. Any wisdom out there? STFA but no answers... Many thanks.

05-26-2006, 05:40 AM	#3
Uwe@Ross-Tech.com Audiworld Premium Sponsor Account #: 9886 Join Date: Sep 2000 Posts: 1,996	Those HVAC controllers are pretty fussy about timing and 3rd party USB interfaces are quite poor at maintaining precise timing because they emulate a serial port and this emulation tends to slow things down. -Uwe- __________________ http://www.Ross-Tech.com

05-26-2006, 11:15 AM	#4
ImpellerCDN New Member Account #: 61441 Join Date: Aug 2003 Posts: 23	As I feared. I'll try with my laptop on AC... ...which ups the clockrate by 2x. Since you mention, >>>emulation tends to slow things down it might help with the com timing precision. Let you know. Cheers.

05-26-2006, 09:21 PM	#5
ImpellerCDN New Member Account #: 61441 Join Date: Aug 2003 Posts: 23	Fixed: tweaked usb->serial latency value... From 16ms to 12ms. HVAC now responds on both my B5 cars. Other controllers seem happy too. Cheers

05-27-2006, 09:03 AM	#6
Bracketracer Elder Member Account #: 1718 Join Date: Mar 2000 Posts: 15,528	actually, I've got to disagree here... I've got the real thing (Hex-USB with 512.4), and have a LOT of problems connecting, or maintaining a solid connection with HVAC controllers in late '90s and early '00s cars. Flaky enough that I can rarely perform basic settings. __________________

05-26-2006, 04:38 AM	#2
Theresias AudiWorld Senior Member Account #: 77434 Join Date: Jun 2004 Location: Magdeburg, Germany Posts: 1,557	Not the 1st time I see that with 3rd party hardware - doesn't happen with real Ross-Tech hardware. __________________ Sebastian @ Ross-Tech.com

05-27-2006, 10:00 AM	#7
Uwe@Ross-Tech.com Audiworld Premium Sponsor Account #: 9886 Join Date: Sep 2000 Posts: 1,996	As I said, those modules are quite fussy. But the HEX-USB should be able to do it without any problem, if there's no other issues with the PC. What kind of PC? What version of Windows? Have you been to the link below? -Uwe- http://www.ross-tech.com/vag-com/faq_2.html#2.5 __________________ http://www.Ross-Tech.com

05-29-2006, 12:29 PM	#8
nasdaqer New Member Account #: 97057 Join Date: Sep 2005 Posts: 220	how did you fixt the serial latency value? I am having the same problem thanks

08-19-2008, 07:03 PM	#9
Maini Audiworld Junior Member Account #: 38404 Join Date: Jun 2002 Posts: 796	Try this.... http://forums.audiworld.com/vag/msgs/16474.phtml __________________ 2001 A6 2.7T Black/Black 91,000 miles Previous faithful Audi 1996 A6 quattro Sold 92,000 miles 01/05

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