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Author Topic: TP20, duplicated CAN frames/wrong sequence number?  (Read 8204 times)
kuebk
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« on: October 18, 2016, 11:29:35 AM »

While playing with TP2.0 over CAN I started to get duplicated frames or frames with incorrect sequence numbers.

Wrong sequence number:
Code:
  can0  740   [8]  25 00 08 36 40 7C F0 00
  can0  740   [4]  16 00 00 05
  can0  300   [1]  B7
  can0  300   [8]  2D 00 06 76 00 00 01 00
  can0  300   [2]  1E 00                                <- seq=E
  can0  740   [1]  BF
  can0  740   [8]  27 00 08 35 50 03 AC 00
  can0  740   [4]  18 00 00 24
  can0  300   [1]  A3
  can0  740   [1]  A3
  can0  300   [6]  A1 0F 8A FF 4A FF
  can0  300   [1]  B9
  can0  300   [6]  1E 00 00 02 75 FF            <- seq=E, shouldn't be F?
  can0  300   [6]  1E 00 00 02 75 FF
  can0  300   [1]  A8
  can0  740   [1]  A8

Duplicated frames:
Code:
  can0  740   [8]  2D 00 08 35 50 24 19 00
  can0  740   [4]  1E 00 00 04
  can0  300   [1]  BF
  can0  300   [5]  1B 00 02 75 FF                <- first occurrence
  can0  740   [1]  BC
  can0  740   [8]  2F 00 08 36 50 24 19 00
  can0  740   [4]  10 00 00 04
  can0  300   [1]  B1
  can0  300   [5]  1B 00 02 75 FF                <- second occurrence

How should I handle both of these?

Thanks.
« Last Edit: October 18, 2016, 01:27:26 PM by kuebk » Logged
andrew
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« Reply #1 on: October 19, 2016, 04:53:37 AM »

You should say something (ACK this or ACK older frame again ) otherwise peer it can drop connection as in 1st case,
if you respond it will continue with new data or retransmit contentious frame

in 2nd case you should ACK again obviously peer doesn't received your ACK
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SKOLS
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« Reply #2 on: October 19, 2016, 05:20:33 AM »

Hi kuebk....

Here is a typical frame from a TP2.0 MED9 (S3 8P) open session :



ID:   0x200   Len:   7   Data:   0x1F   0xC0   0x00   0x10   0x00   0x03   0x01   
ID:   0x21F        Len:   7   Data:   0x00   0xD0   0x00   0x03   0x2E   0x03   0x01   
ID:   0x32E   Len:   6   Data:   0xA0   0x0F   0x8A   0xFF   0x32   0xFF      
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x32E   Len:   5   Data:   0x10   0x00   0x02   0x1A   0x9B         
ID:   0x300   Len:   1   Data:   0xB1                     
ID:   0x300   Len:   8   Data:   0x20   0x00   0x30   0x5A   0x9B   0x31   0x4B   0x30
ID:   0x300   Len:   8   Data:   0x21   0x39   0x30   0x37   0x35   0x33   0x30   0x4B
ID:   0x300   Len:   8   Data:   0x22   0x20   0x20   0x30   0x31   0x37   0x30   0x10
ID:   0x300   Len:   8   Data:   0x23   0x00   0x00   0x00   0x00   0x00   0x00   0x00
ID:   0x300   Len:   8   Data:   0x24   0x18   0xAA   0x4A   0x35   0x33   0x33   0x5F
ID:   0x300   Len:   8   Data:   0x25   0x5F   0x47   0x61   0x74   0x65   0x77   0x61
ID:   0x300   Len:   8   Data:   0x26   0x79   0x20   0x20   0x20   0x48   0x31   0x32
ID:   0x300   Len:   2   Data:   0x17   0x20                  
ID:   0x32E   Len:   1   Data:   0xB8                     
ID:   0x32E   Len:   5   Data:   0x11   0x00   0x02   0x1A   0x91         
ID:   0x300   Len:   1   Data:   0xB2                     
ID:   0x300   Len:   8   Data:   0x28   0x00   0x11   0x5A   0x91   0x0E   0x31   0x4B
ID:   0x300   Len:   8   Data:   0x29   0x30   0x39   0x30   0x37   0x39   0x35   0x31
ID:   0x300   Len:   6   Data:   0x1A   0x20   0x20   0x20   0x20   0xFF      
ID:   0x32E   Len:   1   Data:   0xBB                     
ID:   0x32E   Len:   1   Data:   0xA8                     
ID:   0x300   Len:   1   Data:   0xA8                     
ID:   0x200   Len:   7   Data:   0x01   0xC0   0x00   0x10   0x00   0x03   0x01   
ID:   0x201   Len:   7   Data:   0x00   0xD0   0x00   0x03   0x40   0x07   0x01   
ID:   0x740   Len:   6   Data:   0xA0   0x0F   0x8A   0xFF   0x32   0xFF      
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   5   Data:   0x10   0x00   0x02   0x10   0x89         
ID:   0x300   Len:   1   Data:   0xB1                     
ID:   0x300   Len:   5   Data:   0x10   0x00   0x02   0x50   0x89         
ID:   0x740   Len:   1   Data:   0xB1                     
ID:   0x740   Len:   5   Data:   0x11   0x00   0x02   0x1A   0x9B         
ID:   0x300   Len:   1   Data:   0xB2                     
ID:   0x300   Len:   8   Data:   0x21   0x00   0x30   0x5A   0x9B   0x38   0x50   0x30
ID:   0x300   Len:   8   Data:   0x22   0x39   0x30   0x37   0x31   0x31   0x35   0x48
ID:   0x300   Len:   8   Data:   0x23   0x20   0x20   0x30   0x30   0x34   0x30   0x10
ID:   0x300   Len:   8   Data:   0x24   0x00   0x00   0x00   0x01   0xDC   0x5A   0x10
ID:   0x300   Len:   8   Data:   0x25   0x00   0xBF   0x32   0x2E   0x30   0x6C   0x20
ID:   0x300   Len:   8   Data:   0x26   0x52   0x34   0x2F   0x34   0x56   0x20   0x54
ID:   0x300   Len:   8   Data:   0x27   0x46   0x53   0x49   0x20   0x20   0x20   0x20
ID:   0x300   Len:   2   Data:   0x18   0x20                  
ID:   0x740   Len:   1   Data:   0xB9                     
ID:   0x740   Len:   7   Data:   0x12   0x00   0x04   0x31   0xB8   0x00   0x00   
ID:   0x300   Len:   1   Data:   0xB3                     
ID:   0x300   Len:   8   Data:   0x29   0x00   0x12   0x71   0xB8   0x01   0x01   0x01
ID:   0x300   Len:   8   Data:   0x2A   0x03   0x01   0x02   0x01   0x06   0x01   0x07
ID:   0x300   Len:   7   Data:   0x1B   0x01   0x08   0x01   0x0D   0x01   0x18   
ID:   0x740   Len:   1   Data:   0xBC                     
ID:   0x740   Len:   5   Data:   0x13   0x00   0x02   0x1A   0x9A         
ID:   0x300   Len:   1   Data:   0xB4                     
ID:   0x300   Len:   8   Data:   0x2C   0x00   0x17   0x5A   0x9A   0x01   0xDC   0x5A
ID:   0x300   Len:   8   Data:   0x2D   0x10   0x00   0xBF   0x30   0x30   0x34   0x30
ID:   0x300   Len:   8   Data:   0x2E   0x10   0x09   0x01   0x03   0x00   0x03   0x18
ID:   0x300   Len:   5   Data:   0x1F   0x0F   0x01   0x60   0xFF         
ID:   0x740   Len:   1   Data:   0xB0                     
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   5   Data:   0x14   0x00   0x02   0x1A   0x91         
ID:   0x300   Len:   1   Data:   0xB5                     
ID:   0x300   Len:   8   Data:   0x20   0x00   0x11   0x5A   0x91   0x0E   0x38   0x50
ID:   0x300   Len:   8   Data:   0x21   0x30   0x39   0x30   0x37   0x31   0x31   0x35
ID:   0x300   Len:   6   Data:   0x12   0x42   0x20   0x20   0x20   0xFF      
ID:   0x740   Len:   1   Data:   0xB3                     
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      

You must return an ACK (A3) to keep the session "alive"....


And here is a typical TP2.0 frame of measure block (IE MB 001) :


ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   5   Data:   0x15   0x00   0x02   0x21   0x01         
ID:   0x300   Len:   1   Data:   0xB6                     
ID:   0x300   Len:   8   Data:   0x23   0x00   0x1A   0x61   0x01   0x01   0xC8   0x00
ID:   0x300   Len:   8   Data:   0x24   0x05   0x0A   0x71   0x14   0x32   0x80   0x10
ID:   0x300   Len:   8   Data:   0x25   0xFF   0xB2   0x25   0x00   0x00   0x25   0x00
ID:   0x300   Len:   8   Data:   0x16   0x00   0x25   0x00   0x00   0x25   0x00   0x00
ID:   0x740   Len:   1   Data:   0xB7                     
ID:   0x740   Len:   5   Data:   0x16   0x00   0x02   0x21   0x01         
ID:   0x300   Len:   1   Data:   0xB7                     
ID:   0x300   Len:   8   Data:   0x27   0x00   0x1A   0x61   0x01   0x01   0xC8   0x00
ID:   0x300   Len:   8   Data:   0x28   0x05   0x0A   0x71   0x14   0x32   0x80   0x10
ID:   0x300   Len:   8   Data:   0x29   0xFF   0xB2   0x25   0x00   0x00   0x25   0x00
ID:   0x300   Len:   8   Data:   0x1A   0x00   0x25   0x00   0x00   0x25   0x00   0x00
ID:   0x740   Len:   1   Data:   0xBB                     
ID:   0x740   Len:   5   Data:   0x17   0x00   0x02   0x21   0x01         
ID:   0x300   Len:   1   Data:   0xB8                     
ID:   0x300   Len:   8   Data:   0x2B   0x00   0x1A   0x61   0x01   0x01   0xC8   0x00
ID:   0x300   Len:   8   Data:   0x2C   0x05   0x0A   0x71   0x14   0x32   0x80   0x10
ID:   0x300   Len:   8   Data:   0x2D   0xFF   0xB2   0x25   0x00   0x00   0x25   0x00
ID:   0x300   Len:   8   Data:   0x1E   0x00   0x25   0x00   0x00   0x25   0x00   0x00
ID:   0x740   Len:   1   Data:   0xBF                     
ID:   0x740   Len:   5   Data:   0x18   0x00   0x02   0x21   0x01         
ID:   0x300   Len:   1   Data:   0xB9                     
ID:   0x300   Len:   8   Data:   0x2F   0x00   0x1A   0x61   0x01   0x01   0xC8   0x00
ID:   0x300   Len:   8   Data:   0x20   0x05   0x0A   0x71   0x14   0x32   0x80   0x10
ID:   0x300   Len:   8   Data:   0x21   0xFF   0xB2   0x25   0x00   0x00   0x25   0x00
ID:   0x300   Len:   8   Data:   0x12   0x00   0x25   0x00   0x00   0x25   0x00   0x00
ID:   0x740   Len:   1   Data:   0xB3                     
ID:   0x740   Len:   1   Data:   0xA3                     
ID:   0x300   Len:   6   Data:   0xA1   0x0F   0x8A   0xFF   0x4A   0xFF      
ID:   0x740   Len:   5   Data:   0x19   0x00   0x02   0x21   0x01         
ID:   0x300   Len:   1   Data:   0xBA                     
ID:   0x300   Len:   8   Data:   0x23   0x00   0x1A   0x61   0x01   0x01   0xC8   0x00
ID:   0x300   Len:   8   Data:   0x24   0x05   0x0A   0x71   0x14   0x32   0x80   0x10
ID:   0x300   Len:   8   Data:   0x25   0xFF   0xB2   0x25   0x00   0x00   0x25   0x00
ID:   0x300   Len:   8   Data:   0x16   0x00   0x25   0x00   0x00   0x25   0x00   0x00
ID:   0x740   Len:   1   Data:   0xB7                     
ID:   0x740   Len:   5   Data:   0x1A   0x00   0x02   0x21   0x01         
ID:   0x300   Len:   1   Data:   0xBB                     
ID:   0x300   Len:   8   Data:   0x27   0x00   0x1A   0x61   0x01   0x01   0xC8   0x00
ID:   0x300   Len:   8   Data:   0x28   0x05   0x0A   0x71   0x14   0x32   0x80   0x10
ID:   0x300   Len:   8   Data:   0x29   0xFF   0xB2   0x25   0x00   0x00   0x25   0x00
ID:   0x300   Len:   8   Data:   0x1A   0x00   0x25   0x00   0x00   0x25   0x00   0x00
ID:   0x740   Len:   1   Data:   0xBB                     
ID:   0x740   Len:   5   Data:   0x1B   0x00   0x02   0x21   0x01         
ID:   0x300   Len:   1   Data:   0xBC                     


SKOLS
« Last Edit: October 19, 2016, 05:29:10 AM by SKOLS » Logged
kuebk
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« Reply #3 on: October 19, 2016, 02:08:05 PM »

You should say something (ACK this or ACK older frame again ) otherwise peer it can drop connection as in 1st case,
if you respond it will continue with new data or retransmit contentious frame

Yep I should reply with ACK, but I thought that sequence numbers should follow each other.

in 2nd case you should ACK again obviously peer doesn't received your ACK

Thanks, after ACK the 2nd occurence of will I need to send again 0x36 dataTransfer request?

@SKOLS, thank you for your examples and tips.

I have managed to successfully establish session and use services, issues start to appear after 20-30 (or sometimes even more) minutes of continuous communication.
« Last Edit: October 19, 2016, 02:34:24 PM by kuebk » Logged
andrew
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« Reply #4 on: October 20, 2016, 12:56:11 PM »

Yep I should reply with ACK, but I thought that sequence numbers should follow each other.
Generally you are right, normally they are
but it also you can manage to retransmit data (emulate as it would got lost ) - it looks like
"can0  300   [2]  1E 00                                <- seq=E"
got corrupted in peer or your TP20 stack

Thanks, after ACK the 2nd occurence of will I need to send again 0x36 dataTransfer request?
...
Nope
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kuebk
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« Reply #5 on: October 24, 2016, 04:00:30 PM »

I think I have managed to solve my previous issues. Smiley The worst news is that I started to get frames like these:

Code:
  can0  740   [8]  22 00 08 35 40 7C F0 00
  can0  740   [4]  13 00 00 05
  can0  300   [1]  B4
  can0  300   [5]  15 00 02 75 FF
  can0  740   [1]  B6
  can0  740   [8]  24 00 08 36 40 7C F0 00
  can0  740   [4]  15 00 00 05
  can0  300   [1]  B6
  can0  300   [8]  26 00 06 76 00 00 01 00
  can0  300   [2]  17 00
  can0  740   [1]  B8
  can0  740   [8]  26 00 08 35 50 03 AC 00
  can0  740   [4]  17 00 00 24
  can0  300   [1]  B8
  can0  300   [1]  A3
  can0  740   [1]  A3
  can0  300   [5]  18 00 02 75 FF
  can0  300   [6]  A1 0F 8A FF 4A FF
  can0  740   [1]  B9
  can0  740   [8]  28 00 08 36 50 03 AC 00
  can0  740   [4]  19 00 00 24
  can0  300   [1]  BA
  can0  300   [8]  28 00 00 00 00 00 25 76    <- too many bytes before length?
  can0  300   [8]  28 00 00 00 00 00 25 76
  can0  300   [1]  A8
  can0  740   [1]  A8

Code:
  can0  740   [8]  23 00 08 35 40 7C F0 00
  can0  740   [4]  14 00 00 05
  can0  300   [1]  A3
  can0  740   [1]  A3
  can0  300   [1]  B5
  can0  300   [6]  A1 0F 8A FF 4A FF
  can0  300   [7]  15 00 00 00 02 75 FF   <- too many bytes before length? shouldn't it be 15 00 02 75 FF?
  can0  740   [1]  B6
  can0  300   [1]  A3
  can0  300   [6]  A1 0F 8A FF 4A FF
  can0  740   [1]  A3
  can0  300   [1]  A3
  can0  740   [1]  A3
  can0  300   [6]  A1 0F 8A FF 4A FF
  can0  300   [1]  A3
  can0  740   [1]  A3

Generally seems like most of problems arise when ECU sends A1/A3 frames, but I don't understand why. Sad
« Last Edit: October 24, 2016, 04:02:07 PM by kuebk » Logged
kuebk
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« Reply #6 on: October 27, 2016, 12:15:33 PM »

I tried to reply with ACK 9x for "special" frames mentioned in my previous posts and got partial success but still I have no idea why ECU is sending frames with incorrect length. Sad

Code:
  can0  740   [8]  28 00 08 36 50 24 19 00
  can0  740   [4]  19 00 00 04
  can0  300   [6]  A1 0F 8A FF 4A FF
  can0  300   [1]  BA
  can0  300   [8]  26 00 00 00 00 00 05 76
  can0  740   [1]  96
  can0  300   [8]  26 00 00 00 00 00 05 76
  can0  300   [5]  17 00 00 00 01
  can0  740   [1]  96
  can0  740   [1]  97
  can0  300   [8]  26 00 00 00 00 00 05 76
  can0  300   [5]  17 00 00 00 01
  can0  740   [1]  96
  can0  740   [1]  97
  can0  300   [8]  26 00 00 00 00 00 05 76
  can0  300   [5]  17 00 00 00 01
  can0  740   [1]  96
  can0  740   [1]  97
  can0  300   [8]  26 00 00 00 00 00 05 76
  can0  300   [5]  17 00 00 00 01
  can0  740   [1]  96
  can0  740   [1]  97
  can0  300   [8]  26 00 00 00 00 00 05 76
  can0  300   [5]  17 00 00 00 01
  can0  740   [1]  96
  can0  300   [1]  A8
  can0  740   [1]  97
  can0  740   [1]  A8

Above is just a proof of concept, after first ACK 96 complete frame should be handled without sending 96/97 ACKs.
« Last Edit: October 27, 2016, 03:21:55 PM by kuebk » Logged
H2Deetoo
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« Reply #7 on: November 01, 2016, 05:19:00 AM »

I am sorry I have never experienced such packets.
I guess your ecu is to blaim but why ...
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superglitch
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« Reply #8 on: November 11, 2016, 03:53:38 PM »

The ACK of 0x9x is never really used in any of the implementations I've logged.  I would suggest looking at possibly errors with your hardware (resistors between CAN lines and such).
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kuebk
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« Reply #9 on: November 11, 2016, 04:36:37 PM »

It could be a hardware failure, but "that" frames happen after A1 channel param frame only. I'm doing 15 minutes sessions, like 5-10 first session works flawlessly, the later ones are making problems - and that's kinda odd for me. :<

What hardware are you talking about? You meant ECU or CAN2USB?

Checked the resistor between CAN lines and it gives me reading at 118 Ohm, same resistor but not installed reads at 116 Ohm, checked resistance in genuine VCDS and it is 120 Ohm, could that be an issue?
« Last Edit: November 11, 2016, 04:55:10 PM by kuebk » Logged
superglitch
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« Reply #10 on: November 11, 2016, 10:57:59 PM »

Sorry early reply didn't fully inspect your logs.

You need to reply to channel test messages (0xA1 or 0xA3) first refer to SAE J2819 for priorities of TP2.0.

I've logged many different applications, the only time that an 0x9x ACK packet is ever used is when there is a mistake or the tester is sending messages too fast.
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H2Deetoo
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« Reply #11 on: November 12, 2016, 05:51:00 AM »

I did experience ACK of 0x9x packets (see some other post of mine), and handle them appropriately.
So depending on which ecu/sw version this is normal.
However those packets with wrong length I never saw ...
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jasnm
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« Reply #12 on: November 13, 2016, 09:44:10 AM »

I did experience ACK of 0x9x packets (see some other post of mine), and handle them appropriately.

Having spent a fair amount of time (months) decoding TP/KWP2000. I would say 0x9x aren't the norm. As superglitch indicated they either indicating requests are sent too fast or a mistake. Its also important to bear in mind that the ECU will slow its communication down if its busy with higher priority tasks or tight on resources. Hence you aren't guaranteed your responses in a timely manor.
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H2Deetoo
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« Reply #13 on: November 14, 2016, 07:42:15 AM »

>either indicating requests are sent too fast

Well for me this means those packets are normal.
I mean, a tool preferably wants to send as fast as it can and the ecu can slow it down by replying these packets. Nothing strange and normally no problem.
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jasnm
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« Reply #14 on: November 15, 2016, 01:34:04 AM »

>either indicating requests are sent too fast

Well for me this means those packets are normal.
I mean, a tool preferably wants to send as fast as it can and the ecu can slow it down by replying these packets. Nothing strange and normally no problem.

As per the spec, for acknowledge with receiver not ready 9X, the senders needs to wait 100 ms (T_Wait) and then re-transmit TP blocks starting from sequence X. The tool is forced to slow down by the ecu, in fact the ecu can slow you down further by sending subsequent 9X. The overhead for a tool would be to cache the preceding TP blocks for such scenario. It can be further complicated by the possibly that the 9X refers to a TP block from a previous KWP2000 command. Circumventing this by responding with 9X won't always solve the problem as you can't guaranteed what the ecu actually received.
« Last Edit: November 15, 2016, 01:41:23 AM by jasnm » Logged
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