15765-2 with NI products

[JP_V]

Hello,

I've got questions about Automotive Diagnostic Command Set on NI USB CAN interface.

1. Is The Tramsport Protocol ISO 15765-2 handled by The Hardware ?
2. With NI Automotive Diagnostic Command Set on NI USB CAN interface, what are the minimum and maximum  values for the followings protocol parameters :

• STMin
• Timeout FC (Bs)
• Timeout CF (Cr)
• Timeout Br (Timeout between FF and FC)
• Timeout As (max time to send FF, CF, CF)
• Timeout Ar (max time to send FC)

Thank you for your help

Jean Philippe

ARCALE

[Gibson]

1. Is The Tramsport Protocol ISO 15765-2 handled by The Hardware ?
   no, the Transport Protocol is done on host side, but fullfills the ISO 15762-2 timing requirements
   
   
2. With NI Automotive Diagnostic Command Set on NI USB CAN interface, what are the minimum and maximum  values for the followings protocol parameters :
   
   You can manipulate the following parameters:
   
   
   Timeout Diag Command is the timeout in milliseconds the master
   waits for the response to a diagnostic request message. The default is
   1000 ms.
   Timeout FC (Bs) is the timeout in milliseconds the master waits
   for a Flow Control frame after sending a First Frame or the last
   Consecutive Frame of a block. The default is 250 ms.
   Timeout CF (Cr) is the timeout in milliseconds the master waits
   for a Consecutive Frame in a multiframe response. The default is
   250 ms.
   Receive Block Size (BS) is the number of Consecutive Frames the
   slave sends in one block before waiting for the next Flow Control
   frame. A value of 0 (default) means all Consecutive Frames are sent
   in one run without interruption.
   Wait Time CF (STmin) defines the minimum time for the slave to
   wait between sending two Consecutive Frames of a block. Values
   from 0 to 127 are wait times in milliseconds. Values 241 to 249
   (Hex F1 to F9) mean wait times of 100 μs to 900 μs, respectively.
   All other values are reserved. The default is 5 ms.
   Max Wait Frames (N_WFTmax) is the maximum number of WAIT
   frames the master accepts before terminating the connection. The
   default is 10.
   you can overwrite the default values within your application by using Diag Set Property.vi
   

[JP_V]

thank you for the answer but I still didn't know minimum values for those parameters.

for example could I set Cr to 2ms? or Bs to 5ms? I suppose not because Transport protocol is handled by Windows according to your answer of question 1

Thank you for your help

JP

[Ceule]

There are no defined lower limits for these values; you can specify any value down to 0. However, as you correctly pointed out, the timing is done by Windows, and will be subject to the jitter introduced by the OS which can easily be in the order of 10s of milliseconds. It is however hard to give more accurate numbers as the actual jitter is dependent on the workload of the computer.

Christian

[Gibson]

if you need deterministic behaviour USB / Windows may not be best suited, for this use case LabVIEW RT plus NI-XNET CAN would offer much better determinism and less jitter. ADCS is supported on all LV RT targets like PXI and cRIO

[JP_V]

Finally the solution was to choose a concurent USB device that handle Transport protocol (15765-2) in Hardware part (to ensure determistic)

Maybe an idea of improvement for NI CAN interface...

Thank you for your help